4. The Hundred
This move isn’t super easy, but it’s really effective for getting the muscles deep in your stomach, which helps pull things in. Start by lying on a mat with your arms at your sides. Raise your legs to a 45-degree angle and raise your arms several inches off the mat. Pump your hands 100 times, exhaling and inhaling in 5-second increments as you do so. Think you can do it?