The Science of Setting Boundaries When You're Afraid of Rejection

Your nervous system processes social rejection partly using the same region as physical pain. To define boundaries: boundaries are the limits we set to protect our emotional, physical, and mental well-being, and they help communicate how we want to be treated. So when your system is in protection mode, saying “no” feels as threatening as actual danger.

As a therapist working with anxious millennial women, I see this pattern constantly.

Boundaries feel like rejection because, for many, setting or receiving boundaries can trigger emotions similar to being left out or emotionally withdrawn—especially for those with insecure attachment styles or who have internalized societal expectations that prioritize others' needs over their own. This sense of boundaries feeling like rejection is often rooted in past experiences, attachment patterns, and cultural conditioning. Your brain isn’t broken—it’s stuck in an outdated protection mode where social acceptance meant survival.

Boundaries are a form of self-care that state clearly how you would like to be treated. For more on this, see our section on understanding the emotional impact of setting boundaries.

Experiencing negative emotions around setting boundaries is completely normal. For many, childhood experiences where needs were ignored or boundaries were not respected can lead to a fear of setting boundaries later in life.

These past experiences shape how safe you feel asserting your needs. Internalizing rejection often stems from deeply rooted insecurities and past experiences. For some, boundaries can evoke feelings of abandonment, especially for those with anxious attachment styles, as they may fear that boundaries signal being left or rejected. When someone sets a boundary, it can feel like a personal attack, leading to feelings of unworthiness or inadequacy. To learn how attachment styles influence feelings of rejection, explore our detailed analysis.

The Boundary Paradox for Socially Anxious People

If you're reading this, you might already recognize the impossible situation you find yourself in:

• You need boundaries for healthy relationships

• Setting boundaries risks social rejection

• Social rejection is what you fear most

• So you avoid setting boundaries

• This leads to resentment and eventual disconnection

It's a cycle that makes perfect evolutionary sense—but it's not serving you in modern life. For strategies on building your boundary-setting confidence, check out our practical guide.

Why People-Pleasing Is Actually a Clever Survival Strategy

Let's take a moment to understand what's happening in your brain and body when you people-please. This isn't about weakness or character flaws—it's about survival mechanisms that once served an important purpose:

1. Your amygdala activates: When you perceive potential rejection (like when setting a boundary), your brain's threat-detection system 'lights up' like a bonfire on Guy Fawkes.

2. Fight-flight-freeze response kicks in: Your nervous system shifts into protection mode, flooding your body with stress hormones.

3. Prefrontal cortex struggles to regulate: The part of your brain responsible for rational thinking gets overridden, making it harder to assess the actual (usually minimal) risk of setting a boundary.

4. Pattern recognition goes into overdrive: Your brain connects this moment to every past experience of rejection, amplifying your fear response.

This entire process happens in milliseconds, often before you're even consciously aware of it. That's why people-pleasing can feel so automatic and beyond your control. Learn more about why people-pleasing can hinder healthy boundary formation. I made a short video summarising the above here.

The Physical Cost of Constant People-Pleasing

When you're constantly saying "yes" when you want to say "no," your body pays a significant price:

• Chronic stress response: Your body remains in a heightened state of alertness

• Exhaustion: The energy required to monitor others' responses and manage your own emotions is immense

• Sleep disruption: Your mind replays social interactions, looking for signs of disapproval

• Digestive issues: Stress hormones impact your gut health

• Muscle tension: Particularly in your shoulders, jaw, and neck from the constant vigilance

• Lowered immunity: Chronic stress impacts your immune system functioning

This is why breaking people-pleasing patterns isn't just about psychological wellbeing—it's about your physical health too.

The Window of Tolerance Explained

To understand how to change these patterns, we need to talk about your "window of tolerance"—a concept from polyvagal theory that explains your nervous system's capacity to handle stress.

When you're within your window of tolerance, you can:

• Think clearly

• Feel your emotions without being overwhelmed

• Make decisions aligned with your values

• Set boundaries effectively

But when social anxiety pushes you outside this window, you either:

• Hyperarousal: Feel panicky, racing thoughts, heightened vigilance

• Hypoarousal: Shut down, feel numb, disconnect, or "freeze"

Most people-pleasers fluctuate between these states, making boundary-setting nearly impossible.

The Role of Self Compassion

Self-compassion is a cornerstone of setting boundaries and building healthy relationships. When you approach boundary setting with self-compassion, you give yourself permission to prioritize your own needs and emotional well-being, even when it feels uncomfortable or unfamiliar. For many people, especially those who have struggled with low self-esteem, negative beliefs, or a history of emotional or physical abuse, the idea of putting boundaries in place can trigger anxiety or a sense of guilt. You might worry that setting boundaries will make you seem selfish, or fear that others will feel rejected or hurt.

But practicing self-compassion means recognizing that your needs matter just as much as anyone else’s. It’s about understanding that healthy boundaries are not a form of rejection, but a vital part of self care and emotional maturity. When you treat yourself with kindness and understanding, you’re better able to acknowledge your feelings—whether that’s sadness, anxiety, or even anger—without judging yourself or pushing those emotions aside. This self-awareness is essential for communicating your limits clearly and respectfully, and for maintaining your own well-being in any relationship. For tips on how to manage guilt and negative beliefs around boundary setting, see our guide.

Self-compassion also helps you reframe the way you interpret boundaries—both your own and those set by others. For example, if a friend or partner puts boundaries in place, it’s easy to take it personally and feel rejected or abandoned. However, with self-compassion, you can remind yourself that their boundaries are about their own needs and limits, not a reflection of your worth or value as a person. This shift in perspective can reduce the sting of rejection and help you respond with understanding and respect, rather than hurt or resentment.

Cultivating self-compassion is an ongoing process, not a one-time achievement. It involves regularly checking in with yourself, acknowledging your emotions, and giving yourself the same care and compassion you would offer a friend. Simple self-care practices—like journaling about your feelings, meditating, or taking time for quiet reflection—can help you build emotional resilience and a stronger sense of self-worth. Over time, this makes it easier to set and maintain healthy boundaries, communicate your needs, and create relationships that are balanced and fulfilling.

Ultimately, self-compassion is essential for anyone struggling with boundary setting. It allows you to move past negative beliefs and old patterns, and to approach both yourself and others with greater empathy and understanding. By making self-compassion a daily practice, you lay the foundation for emotional well-being, healthier relationships, and a life that honors your own needs as much as those of the people around you.

Breaking the Pattern: Evidence-Based Approaches

Through my work with clients using ERP (Exposure and Response Prevention) and ACT (Acceptance and Commitment Therapy), I’ve developed a framework that addresses both the psychological and physiological aspects of people-pleasing. It’s important to remember that practice setting boundaries is a skill that takes time, effort, and repeated practice to master. Consistency in upholding boundaries is also essential for reinforcing their importance to others.

1. Build Awareness of Your Warning Signs

Start by noticing your physical responses before people-pleasing:

• Tightness in your chest

• Quickened breathing

• Stomach churning

• Voice changes (higher pitch, quicker pace)

• Feeling small or wanting to physically shrink

These sensations are your nervous system's early warning system—learn to recognize them before automatic people-pleasing kicks in.

2. Practice Nervous System Regulation

When those warning signs appear, try these regulation techniques:

• Hand on heart: Place your hand on your heart and feel your heartbeat

• Orienting: Notice 5 things you can see in your environment to bring you into the present moment

• Grounding: Feel your feet firmly planted on the floor

• Focus solely on the sounds around you to narrow in your focus to the here and now.

These simple practices help widen your window of tolerance, giving you more capacity to tolerate the discomfort of setting boundaries.

3. Start with Low-Stakes Boundaries

The science of effective boundaries shows that the clearer the boundary, the less anxiety it causes. Begin with low-risk situations:

• "I can't stay late tonight, I have plans"

• "I'd prefer to go somewhere quieter where we can talk"

• "I need a day to think about this before I decide"

These smaller boundaries help build your "boundary muscle" before tackling harder ones. For more on this, see our article on how to communicate your boundaries clearly and effectively.

4. Recognize Common Safety Behaviors That Keep You Stuck

Safety behaviors temporarily reduce anxiety but reinforce the fear long-term. Common ones include:

• Over-explaining your "no"

• Apologising excessively

• Speaking quickly to "get it over with"

• Avoiding eye contact when setting boundaries

• Using softening language ("maybe," "just," "sorry, but...")

While these behaviors feel protective, they actually send signals to your nervous system that boundary-setting is dangerous.

5. Practice Values-Based Boundary Setting

Instead of focusing on reducing anxiety (which paradoxically increases it), focus on what boundaries allow you to live more aligned with your values:

• What matters most to you in relationships?

• How do boundaries help you show up authentically?

• What becomes possible when you protect your time and energy?

This shift from fear-avoidance to values-approach changes how your brain processes boundary-setting.

A Client's Journey: From People-Pleasing to Authentic Connection

A client of mine (whom the details shall remain anonymous and slightly changed to protect privacy) who was a marketing manager, came to therapy exhausted from saying yes to everything. She described her life as “constantly performing” and felt resentment building in all her relationships.

Through our work together, she learned to:

1. Recognise her physical cues before people-pleasing

2. Regulate her nervous system with techniques that actually work, not ones borrowed from TikTok

3. Start with small boundaries at work (“I’ll review this tomorrow”)

4. Gradually build to bigger boundaries with family and friends

5. 
   

Six months later, Sarah reported feeling “like herself” for the first time in years. Her relationships had deepened rather than fractured, and she had more energy for what truly mattered to her. Not to mention way less anxiety overall and going out her comfort zone without panic attacks.

Seeking support from a therapist or counselor can provide valuable guidance in developing emotional resilience and healthy boundary-setting skills, especially for those with deep-rooted trauma.