5. Redline it.
If you’re prepping for a marathon or a century ride, there’s no substitute for long, slow mileage. But for the average guy looking to build cardiovascular fitness while staying lean and muscular, sprinting may be the better choice. Not only are the workouts faster (you can bang one out in less than a half-hour), they’re also better preparation for athletic activities like soccer, basketball, tennis, and other games requiring short bursts of maximum effort.
Every week for four weeks, do two sprint workouts on nonconsecutive days: run on a track on Tuesdays and hit the rowing machine on Fridays, for example. After five minutes at an easy pace, go as hard as you can for 30 seconds to a minute, then rest for 90-120 seconds. Repeat the work-rest cycle six to eight times.