For me, the best realization I ever had about insecurities is that getting over them is usually painful and often awkward, but that's okay, that's just how it is, I can just relax into that. It doesn't make it less painful or embarassing (in fact, I learned a long time ago to repress a lot of emotion, telling myself I was somehow overcoming it... and then later it all comes back out.) But it does make it easier to tolerate, because I have perspective.
Like, I used to be super socially awkward, and always wondered what I could do learn to be more sociable without just suffering through incredibly awkward social situations or forced, unpleasant bouts of faking it, or whatever. Years later, it turns out there wasn't anything I could do; all the social awkward stuff happened, and it sure was awkward, but that's the process, right? It didn't kill me.
Or, God, the first -- man, probably ten or so -- times I had sex I thought I was just going to die of embarrassment, things were so awkward.
The more stuff I go through like that, the more I realize that it's not gonna kill me, and even if it's not pleasant, I learn about a million times more about myself in times of pain than when I'm just sitting around being comfortable.
To tie this in with the whole RealJock thing, athletics have been a huge help for me in that. Growing up, my parents talked me into trying all sorts of sports. Baseball. Basketball. Etc. Turns out I just didn't like team sports, and other than biking just to get around, I was totally not athletic at all until I turned 22, at which point I picked up the yoga, the climbing, and a couple years later, the road biking. Hell, I was a pretty steady smoker until I was 23.
Through sports I've really developed a different relationship with pain. Used to be I saw pain as an awful thing to be avoided at all costs. Now I see it more subtly. Acute pain is still bad, but burning in the muscles is just telling me something. It doesn't mean I can't hold on or push myself harder.
Similarly, it translates back to real life. Overcoming fears and insecurities, I feel that aversion, this resistance, but I can also recognize how beneficial it is to overcome that stuff, and view the resistance & fear just as information -- telling me to be careful, not to overdo it -- and I can work with that, instead of letting it scare me away.
God, this was a really long post. Sorry about that, I'm lying in bed trying not to fall asleep after a long ride.