The plank is a great way to not only tone your arms, but to work your core muscles as well. Begin with a position similar to a push-up, but instead place your forearms on the floor. Keep your abs contracted while holding your body in a straight line for at least 10 seconds to start (trust us, you will feel the burn). After 10 seconds, take a break and give the plank another try with the goal of working up to holding the position for 30 to 60 seconds. This exercise is a favorite of many celebrities and will get you in tip-top shape fast!