Johanna said keeping a mirror close to her workout space is useful for correcting her form (that's why home workout system Mirror is so effective) — and you likely have a full-length mirror somewhere in your home. As a reminder, being mindful of your form will ensure that you're working the correct muscle groups and getting the most out of your exercises. For example, if you're doing squats away from a mirror, you might not notice that you're breaking your form and leaning your chest forward instead of keeping it upright. It's easier to correct these mistakes if you can actually see yourself doing the moves and making the errors.