It is well known that exercise is one of the best way to prevent some diseases, but now the American College of Sports Medicine (Acms) in its latest Guidelines has stated how much physical exercise is necessary to be healthy.From cardiovascular diseases to diabetes, from hypertension to obesity from osteoporosis to cancer: with a 30 min. daily training for 5 days a week (150 min. /week) adults between 18 and 65 years old may prevent all these diseases. The best training strategy is to do some aerobic activities (running, swimming, cycling) together with some stretching and muscle strengthening exercises. Alternatively, as suggested by a new study carried out by the University of Leicester and published on The Lancet it is advisable to walk for 20 minutes per day to reduce body weight and to decrease the risk of developing cardiovascular diseases by 8%.