Swimming is a great cardiovascular workout. It works all of the large muscle groups in your body and is especially ideal for people who have joint problems, problems with overheating, or are too obese for weight bearing exercise yet. Make sure that you are a proficient enough swimmer to get your heart rate into its target range and swim continuously for at least 20 – 30 minutes. Some people may need stroke instruction before being able to use swimming as a fitness activity. Check with your local recreation department or a private swim club for adult lessons. Many areas have masters programs for adult swimmers that can provide stroke instruction as well as group workouts. Remember to always put safety first and never swim alone.