There should always be 3 parts to a warm up: a general warm-up, a joint specific warm-up and an exercise practice warm-up. For example, today is bench press day. I would start with a walk on the treadmill, forward circles with my arms and 3 very light weight bench press sets with no more than thirty percent of my maximum weight. If you have diabetes, high blood pressure or high cholesterol, it's even more important to warm up. The older you get, the more important warming up becomes.