“It’s done. I made the decision and it’s done. Or, maybe I should have done it differently, made a different decision. What will they think of me? What if I’m wrong? Why did I ever get myself in this position? Oh, no, I’m the one that’s done!”
Considering the possibility that you might be wrong is a good leadership characteristic, when properly used. It says you’re willing to acknowledge that you don’t have all the answers and you’re willing to listen to the ideas of others. Ruminating makes us look wishy-washy or lacking confidence. Those looking up to you for leadership may begin to doubt as well.
There was a time many years ago when I hired the wrong guy. He happened to have the same name and work for the same company in the same area of expertise as another very qualified individual. The interview seemed inconsistent with his professional reputation, yet all the references were good.
What could I do? Worry, second guess, ruminate? Or just get on with it and do the best I could in the situation moving forward. I did the latter and all worked out in the end.
Once you’ve decided a course of action, move forward with conviction. If you get new information, use it to course-correct. But absent new information, persist, breathe deeply and let it go.