Just do it
You know you can do it. You just have to say it to yourself enough and then of course believe it. Then it's just a question of doing it. The doubt is normal. But the more you push, the more what once seemed challenging seems normal and the further you raise your bar. Believe in yourself and set yourself free. Commit to yourself and make deep, meaningful changes to your life. You might not feel ready but what does feeling ready feel like. Do it any way.