Plank
How to do it: Get in a press-up position, but rest on your forearms rather than your hands. Make sure your back is straight and tense your abs and glutes. Hold without allowing your hips to sag.
How do you know if you are doing plank correctly?
Your arms should feel engaged, but comfortable—not as if they're about to give out. 2. Doing a plank may target the abs, but your legs should feel a little burn too. If they don't push back through your heels and push the balls of your feet into the floor.