Holding your breath can let you know whether your lungs are healthy or not. When swimming or taking a bath, take a deep breath first, then bury your head in the water, hold your breath, and then exhale slowly to see how long it can last. Of course, the longer the better. If it is more than 30 seconds, it means that your lungs are healthy; If you can reach 1 min, your lungs will be strong.
2. Stand on one foot to check the aging degree.
Subjects' hands droop naturally, cling to thighs, close their eyes, stand on one foot, and the other person looks at a stopwatch. Judging the aging degree according to the time when one foot is independent and stable.