How to quickly restore fitness level after stopping fitness for a long time?

The more muscles you have, the less time it takes to get back into shape. Muscle memory will last for a long time after muscle fat reduction. Therefore, recovery training can make muscles, blood vessels and lungs recover quickly and make them reappear, and lose some weight in the process. Keep the strength low. As long as there is no excessive pain, you can move up gradually. Don't change so quickly to increase strength. Don't do too much, especially in the first week. Choose some exercises (ideally compound movements, such as squat, hard pull and bench press), and do one set at a time for the first exercise. It is necessary to restore the connective tissue of the body slowly, not in a hurry to restore the previous state, but step by step.