How Can I Stop Self-Doubt from Causing Stress and Failure?

Q: Dear Todd, in my case, all my stress and chronic anxiety come from insecurities and a lack of self-worth. I'm selfish and unkind to people sometimes, but it's not because I want to be; it's because of how I feel about myself. Every moment of my life, I feel I'm not enough and am always afraid of failing. So I stress and stress, can't sleep, and end up failing.…