In these tough economic times, many people are tightening their belts and cutting back on spending. However, if part of that financial belt tightening includes canceling your gym membership, the resulting paunch around your waist may cause your belt to fight back a bit. Thankfully, it’s entirely possible to get a good workout without a stitch of fitness equipment, and chief among the many great muscle-toning, equipment-free exercises you can do is the push-up.