Have you noticed the great feeling you have after a good workout? I have and once you have made it over the initial first few weeks of using fitness equipment for a workout the body seems to crave a good workout at least every other day. Once I have reached this point in my physical workout's I look froward to using my fitness equipment and working up a good sweat. The body releases certain chemicals during strenuous exercise that we all have but do not gain the benefit from unless you really push yourself physically. Some long distances runners have called this release of chemicals the "runners high" due to feeling of calmness and ability to continue to run for very long distances. I have experienced this a few times when riding my ten speed bike long distances. for me I pass into this "high" after thirty to forty miles and and when it hits I feel like I can continue to ride forever. It is really something and the only way I have found to achieve this feeling is a good hard physical workout. 
workout, fitness equipment