Just to +1 this, but once you push yourself out and get a little success, it lets you rewrite your mental model. You say "Oh, that's funny. That girl liked me even though I have these scars." Then next you say "Wow, that girl saw me naked and she didn't even object, we just had sex. Maybe she didn't notice?" Then later on you say "I've had a few really beautiful girlfriends now who didn't even pay attention to these things about my body I thought were just total deal breakers. Are these chicks weird or have I been worried about stuff many girls don't care about?"
And then eventually you reach a point where you maybe still aren't a huge fan of whatever it is you don't like about your body but you don't think about it, worry about it, or care about it anymore at this point because time has taught you nobody else does.
You may also want to check out this article on physical insecurities by Darius.
For my money though, there's nothing that wipes away worries about trivialities (that feel like monumental issues at first) quite like success.