This answer may seem off topic, but I started paying closer attention to my own sense of fear and seeing what brought it out and what chilled it out. I started noticing that certain experiences really slammed my sense of self-worth. I also noticed that others could increase my sense of self-worth. So I started setting a target for myself. I assigned points to certain things I could do that helped my self worth (for me it was things like cleaning a room or getting laundry accomplished, nothing major). The point value increased compared to how much I disliked the task.
I decided that I was going to try to earn about 100 SW (self-worth) points every day. If something occured that knocked me back, then I needed to earn that many more points. It took a while to build up to this, but when I regularly practice it, I notice that my fear minimizes drastically. It builds my confidence. When I know that I am actively doing things that make me feel better about me, I have a different sense of being able to stand up for myself. The horrible feeling in my stomach goes away and I find that I stand up straighter.