You won’t have to spend money on a gym and special equipment — all you need is willpower and 10 minutes a day.
How to do it: Plank is an isometric (static) exercise where the rule is to hold your body correctly. Follow the example above: keep your back and legs straight without sagging or arching.
Results: If done correctly, the exercise works the abs, back, buttocks, legs, and arms. It also improves posture and general muscle tone.