Since I started playing tennis about 2 years ago, I noticed the importance of breathing and relaxing in playing good tennis. Many times, I got into a frustrating situation that I missed many shots in a row. Typically, it happened because in trying to concentrate under pressure, I stopped breathing regularly and started contracting different muscle groups. I have also seen the same situation happening to many novice players.
The interesting point here is that "bad breathing and tension induces a pattern of repeated errors." I believe this is generalizable to other physical activities, but I am curious if it applies more generally to our decision making in life.