Lots of folks say you should “believe in yourself.” What they fail to recognize is that belief isn’t something you can just switch on.
If you haven’t proven in your past actions that you are brave, skilled, or wise, you simply won’t be able to muster belief that you are brave, skilled, or wise. You lack self-credibility.
You’re in a chicken or egg situation: you need to act in order to believe in yourself, but you also don’t believe in yourself yet.
The answer lies not in believing in yourself but in believing in action. You may have no reason to believe that “you” will be able to do something. You can look at history and your own experiences to know that a specific, concrete action *will* achieve something – even if it’s done by little old you.
You can believe in running, rather than yourself as a runner. You can believe in writing, even if you don’t believe in your writing skill. Do whatever it takes to believe in action so compelling that it causes you to act. Then you can start believing in yourself – you will have acted.