How do you think the following quote from "The Fearless Mind" relates to performance?

p. 18 Controlling emotions provides an individual with the ability to think rationally and reasonably, increasing the ability to learn from life events and perpetuate growth; hence, emotional energy is needed to get things done. However, when there is an abundance of emotional energy, it can cause destructive behavior as well. When we lose control of our emotions, we aren’t thinking anymore; we are worrying. When we worry, our minds race, attending to events that occurred in the past and then jumping to events that might occur in the future.