Looking for the most efficient way to get your muscles working? Science has the answer, and you'll be surprised at how simple it is.

And the day after that. More than 3,700 days later, he hasn't missed a single day of exercise, though he does take some easier days of light cardio to give his body a chance to recover.

Cardiovascular exercise, aka cardio ... start with weights and finish with 15 to 20 minutes of light cardio. If endurance is your goal, start with cardio and follow up with a lighter strength ...

The winter flu season is still in full force, according to the US Centers for Disease Control and Prevention, causing many sufferers to halt their exercise regimen. But not every illness requires you ...