Like nutrition advice, exercise advice seems to change as often as clothing fashion changes. It can be hard to keep up, and easy to get skeptical that any advice is solid. However, if you want to keep up and are not skeptical, read this: How Smart Exercise Keeps You Younger for Longer.
My take, which is a variation of this, is simple: do a range of exercises, from cardio, to strength, to stretching to balancing. A fitness routine that includes all this is better than a fitness routine that just focuses on one or two areas. And any fitness routine is better than no fitness routine.