Self-doubt, self-examination, and self-criticism have one thing in common - they are all focused inward. That is a dangerous place for a leader to dwell. I am not suggesting that you should not have some introspection. But if you stay there long you will miss what's right in front of you.
First, set limits. When you make a major decision allow yourself a set period of time to express doubt (i.e., two hours). After that, refuse to second-guess yourself with your thoughts or your words.
Second, limit self-examination to a certain time each week (i.e. Friday morning). The other days of the week, don't waste any time reviewing your mistakes.
Third, no one is perfect. In fact, if you go through life demanding perfection or nothing, what are you going to get? What I am about to say may surprise you, but I am serious, never engage in self-criticism. If you have allowed yourself time for purposeful self-doubt and examination, then self-criticism isn't necessary. When is the last time someone criticized you and you thought, "I love this! I want more!"
Lasting Leaders have a healthy opinion of themselves and an intense focus on what's in front of them and beside them - they are not obsessed with what's inside!