Basically all I do is sit-ups, push-ups, flutter kicks, and leg raises, then run. However, I do incorporate variations of those exercises. For instance, I'll use the declined sit-up bench, bring my back perpendicular to the seat while holding a medicine ball outstretched in front of my torso. Then I go right, middle, left, and back many times w/ the ball going for the ride out front. Works your lower back and gets that nice line...plus the obliques get a nice workout too.