Anxiety is the leading cause of health related issues. Anxiety triggers the release of cortisol in the brain. The cortisol leads to uneasiness, lack of sleep, lack of appetite or cause of over appetite. Anxiety produces headaches, ulcers, general gastrointestinal issues and overall "stress". Frequent exercise reduces anxiety by releasing serotonin. Pair that, with building confidence in an area of focus and anxiety can be reduced tremendously. Sports are able to provide an area of focus and frequent exercise.
More information on anxiety, causes and cures check out the links below.