"You've been criticizing yourself for years and it hasn't worked. Try approving of yourself and see what happens."- Louise Hay.
I have been guilty of criticizing myself because, things failed to pan out in the past and have never really taken it upon myself to try doing the opposite.
Being able to criticize oneself is kinda like a status stripe because, we get used to being that way after series of swipes from society about how we have failed or have fallen below expectations.
To make a difference with your life, you do not really need a manual. You need to try approving of yourself and your methods, it doesn't get better than that if all you ever truly want to be, is good at what you do.
Stop making your story about how you have failed in the past, and try making it about who you are, while doing the best you know how to do.
Failure makes good bedfellows while success stays more unhinged with us because we mostly fail to call it into being in the real sense of the word.
Approve of yourself and your methods and don't allow what society projects on you to form your conversation about yourself and life.
Give yourself a hand of applause for everytime you fail or make a blunder at something, that way, you will truly be able to appreciate every single effort you put out to be you.