There is a set of management mistakes that managers make over and over again. Especially likely for newer managers, but it happens to more experienced people too. I’ve made all of these mistakes.
Focusing on past accomplishments creates obstacles to success in the present. If you're still talking about something great you did 20 years ago like it was yesterday, your ego is getting in the way.
What you did in the past makes a good story. What you're doing now makes a difference.