Swimming can be used as a warm up session before going to your regular works. After work, swimming few laps will able to assist you cool-down, it moves blood all the way through your muscles helping them to recover the strength, and relax you. If your weight is 150 lbs. then you will burn nine hundred calories in 1 hour by swimming only 30 minute, a mile. On the other hand, many swimmers don't swim quick and for that much distance.