Imagine two things...
Think of a situation where you don't feel comfortable being yourself.
For me, today, it was being in a crowded gym in another city. I felt like everyone was watching me, and of course, judging me.
Now, in the same situation, imagine how you would feel if you allowed yourself to not care about what others think of you. Just for a moment. Let yourself breathe it in for a while. You can go back if you'd like to.
Now, also imagine that everyone there is completely supportive of you and sending you positive wishes as you do what you seek to do. Feel what that feels like.
Now, go back to how you were feeling earlier.
Keep going back and forth and see which state of feeling you prefer.
Also, see how when you go back and forth, it's easier to go in one direction and not the other.
Once you get comfortable with this, try it in different spaces where you don't feel comfortable being yourself.
HT to Martha Beck for teaching a version of this exercise in her book, The Way of Integrity.