That things happen. That this life is a test. A test of faith and attitude and endurance.
I have also been down on myself (unfortunately I am my own worst critic). Mainly I have been comparing myself to others. Comparing others successes to my downfalls and their strengths to my weaknesses. I feel things and people are purposely working against me. I never feel good enough sometimes ... most times in some particular areas of my life. I feel like I try and try and try and always come up short. Never good enough. I wish I could be specific but alas, as usual, details are not a good idea. You're gonna have to settle for another quote.
