How do I improve my self-image?

I have lots of career failures (more like not achieving those goals) in life. A few personal failures as well.

One thing I realized after talking to a good friend is that I have a negative image of myself which is why I never take bold steps or back out even if the opportunity is in front of me or seem helpless most of the time.

I'm looking for suggestions from the HN community on how to overcome my obstacles. Has anyone here had a negative self-image in the past and their life improved dramatically after they got a positive self-image of themselves?