One way to restrain our tendency toward overconfidence is to habitually position ourselves in such a way that renders a prediction of the future unnecessary.
You might not know with certainty when the 100-year flood is coming, but you do know with certainty it will come. And that means you should leave yourself positioned accordingly.
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.