Forget about all the excess movement and back straining that comes with crunches. The plank pose is the real basic building block for all ab exercises. Just put your elbows on the floor and hold the rest of your body straight, not letting your back or legs sag toward the floor (you can also keep your arms outstretched, but most find that a bit easier). If you can’t make it to two minutes, scope out some other exercises to build up your abdominal strength and you should get there soon. If you can knock out two minutes easily, simply see how long you can go or add some modifications. Do a regular plank for the first minute, lift your left leg for the second minute, and lift up your right leg for the third. Or, balance your forearms on a foam roller or find some other tough variation.