When I talk with people about my manager development program, I get a great deal of encouragement. The most common phrase I hear is "That is awesome, I know a lot of people who could use that". I appreciate the kind words, but there is a part of me (way back in the deep recesses of my mind) screaming "what about you?"
I don't necessarily think they need the help, but I know scientific research shows one of our greatest weaknesses is self-awareness. It is the rare person who really knows their strengths and weaknesses. The research shows only between 10-15% of people can be considered self-aware.
To be a great manager, you have to constantly be thinking "what about myself don't I know" and "where can I be better". It can take time and it can be painful. It can also be liberating and push you to levels of success you never imagined.
I'm working on creating a questionnaire to help you determine if you are a great manager or not. In the meantime, do some brutal self-assessment. If you think you are great, you could be (and I hope you are). You could also be missing things that others are seeing clearly.
Also keep in mind the Dunning Krueger Effect. My children remind me of this all the time when I tell them I am funny.