Tips to build your muscle mass at any age - MSNBC

If you think 20 to 30 minutes of cardio a few days a week is all you need to keep your health in check over the next few decades, it's time to wake up and smell the iron.

In August, the American College of Sports Medicine and the American Heart Association updated their physical activity guidelines, encouraging Americans to strength-train at least twice a week and work out all of the major muscle groups on top of regular cardio activity.