Your mind has to be connected to your body. This cannot happen if your mind is in your kitchen trying to decide what’s for dinner. This cannot happen if your mind is in 1989 wishing the mouth had said something at that insult. Your mind cannot be in your body if it is noticing all the other people in yoga class who are better/worse/prettier/uglier/skinnier/fatter than your body. So how do you get your mind connected to your body? Well, just tell your mind to stay put. Tell your mind to be in THIS body. Your mind may try to wander and try to be in the body that is similar, but 15 years younger and with fewer injuries. Tell your mind to stay here.
Remind your mind that if it wanders through time it will miss the gift of sitting in meditation. In turn, your body can never understand a pose, never understand a single inhalation, if your mind is off somewhere else.