Push-ups may seem like an old-fashioned way to exercise your arm muscles, but there's a reason why they're the standard arm workout! They also work many other muscles in your body, including your abs, chest and shoulders. The great thing about push-ups is that you can do them no matter what fitness level you're at -- just modify the move to make it easier or more difficult based on your preference and strength level.
For the standard push-up, start out facedown with your hands on the floor a little wider than shoulder-width apart. Place your toes on the floor and create a diagonal incline with your body. Lower and raise your body by bending your arms at the elbow, but make sure to keep your glutes engaged and your body straight. Depending on your strength level, do three sets of 10-15 pushups. To modify them, start out on your knees instead of your toes.