The simple solution is the one you most certainly WON'T do.
Start being social, but not with people where it's easy to be social with.
Start being social (approaching, starting conversations, etc.) with people where you FEEL NERVOUS before doing so.
If you can't do that, you'll NEVER GET THE GIRLS YOU WANT.
If your body is weak, you improve it with exercise.
Exercise is repetitive motion that is NOT COMFORTABLE.
If your social skills are weak, you must improve them with exercise.
Exercise is repetitive behavior that is NOT COMFORTABLE.