Thinking in Public
In 1977 the psychologist Albert Bandura introduced the idea of self-efficacy: your confidence that you can take the actions needed to reach a goal. People with high self-efficacy make more effort and keep at a task longer than people with low self-efficacy.
Bandura named four sources for it: doing the thing and succeeding, watching someone like you succeed, being encouraged by others, and how you read your own body and mood. The most effective of the four is to do the thing and succeed. Start with something small enough to win today.
I think a belief like this is a habit. Say the sentence about yourself out loud before the hard thing, then do the first small step while it is still in your head.
Write your own version of the title. One sentence, in your words, that you would be glad to hear a friend say about you. Read it tomorrow morning.