Physical exercise is an activity to improve and maintain physical shape, as well as overall health and well-being. Fitness and Bodybuilding exercises help you strengthen the muscles and the cardiovascular system, improve athletic skills, lose weight, gain weight or maintain your body form, stay fit or transform your body. Frequent and regular exercise stimulates the immune system and helps prevent various cardiovascular diseases, diabetes and obesity. Fitness and Bodybuilding exercises can also improve mental health, help prevent depression, contribute to developing and maintaining high self-esteem. Physical exercises are also very effective against childhood obesity, a growing global problem.