If at all possible, try to work out in front of a mirror, Dr. Carter suggested. "If you're confident that you are doing the proper technique, this is a good time to be in front of a full-length mirror, so you could be actually critiquing your own form." (One trainer talked about this in a previous interview.) That's another reason working out with a friend at home can be beneficial. Aside from keeping each other on track and accountable, they can focus on your form as well. And, Dr. Carter stressed the importance of finding a community to be active with. She, in fact, pointed to the November Project, which is essentially free large-group workouts that happen outside the confines of a gym.