Nike Training Club
Cost: Free; Premium subscriptions start at $15 per month
If you want the experience of working with a trainer, but the convenience of doing it at home, download the Nike Training Club app. Each of the exercises is demonstrated by a trainer, making it much simpler to focus on your form. Plus, you can choose your workouts by type, muscle group, and more. When you subscribe, you'll also have access to weeks-long programs and nutrition advice.