First and foremost, through exercise, we can speed up the body's metabolism and improve immunity, thus reducing the occurrence of colds, which can be done. You can see many old people who like to run in the morning or play Tai Chi. Although I am very old and my resistance is weakening, I seldom get sick, which is achieved through fitness.
Secondly, for some obese people, they are more likely to suffer from hypertension and hyperlipidemia, but controlling weight and reducing body fat through fitness will help reduce diabetes caused by obesity, which is also a major manifestation that fitness can prevent diseases.
Another thing that is most easily overlooked by all of us is that fitness can prevent our mental illness, because people who exercise regularly are very self-disciplined and feel very happy every time they finish fitness. Through long-term fitness, you can keep yourself in good condition and increase your self-confidence. For many people who are not confident enough and cheerful enough, fitness can help them very well.
It should be noted that we should not blindly pursue the results of fitness, but enjoy the process happily. If you are really not interested in fitness, don't do it specifically to prevent diseases, which is not conducive to your physical and mental development. We can see from many news that people who don't know their physical condition because of excessive exercise will be more dangerous in the process of exercise.