When I was young, did a lot of mistake. Almost of the results are bad. Though I'm rolling forward day by day to get the best, past experiences do to feel worry. If we are worry for the things that we've to carry out, then no mission complete in time is sure. As more and more we allow this, lack of confidence and start to coward. But the reality is I could 75% just a few percentage I couldn't. Because of worry and anxious, we focus on imperfect, uncompleted equipment and facility, past experience and blaming of others.
So the true thing is worry make us to be a stupid.