To successfully work thru what's holding you back - sometimes it's just necessary to fake yourself into it - use the analogy that you're an actor performing in a role. When you have to turn on the switch for performance - you have to also turn off the power switch to the obstacles in your mind. For the duration of the performance - it's key that you believe in yourself in order for your audience to believe in you.

We all doubt ourselves. Just go for it & strive to continually strengthen your belief in yourself.