t’s 80 percent diet and 20 percent exercise! What you’re taking in is just as important as the abs series. My all-time favorite tummy-flattening technique is the plank. You can do a moderated or full plank version and can add to the series by dropping your knees and tucking your foot to the side while still in a plank position. It’s important to use correct form so your knees are under your shoulders, your navel is toward your spine, and your neck is relaxed and elongated.