The choice of exercise should be gradually adjusted according to your physical condition and fitness progress. Generally speaking, a single swimming time of 30 minutes to 1 hour is more appropriate. If it is shorter than 30 minutes, the fitness effect may be poor, and if it is too long, it may cause physical discomfort. For beginners or people who have just started continuous swimming and fitness, the body needs to have an adaptation process. You can choose to swim alone for 30 minutes to complete the distance of 600 meters. If you feel that your skills are getting better and your speed and strength have improved to a certain extent, you can gradually increase it to 800 meters, 1000 meters, 1200 meters every two or three months, and the swimming time will be prolonged accordingly, but you must.