(From the IBO Execution Bootcamp where I served as a Faculty member)
Self criticism can be a strength if you learn to balance it with knowledge quests i.e. after beating yourself down, ask yourself what you could have done better. It would hand you 2 tools.
- the knowledge gaps that you can close to help you actually do better next time.
- the realization that some particular situations are out of your control, and there’s little you can do about them.
Number 1 would push you to grow, number 2 would push you to acceptance.