How long is it appropriate to stay in the gym?

This is the worst fitness habit! You are suffering from extreme cold, which is the most harmful to your health and worse than people who don't exercise.

Fitness is a long-term and continuous activity, which can improve all aspects of the body's functions and achieve the purpose of strengthening the body. There is also that your fitness has no purpose, no pertinence, and the effect is definitely not obvious. It will obviously help you to find a professional coach, make some targeted exercise plans according to your current physique, or communicate with people who practice better in the gym and ask for advice.