You step onto the treadmill with good intentions. Set a comfortable pace. Zone out to Netflix for 30 minutes. Check the box ...

Enter: the antidote to punishing workouts with all of the endurance gains.

This writer turned to the treadmill to avoid Houston summers and ended up finding her favorite training tool.

"Hearst Magazines and Yahoo may earn commission or revenue on some items through these links." MY LEGS WERE screaming, my lungs were on fire, and the incline ahead had me stressed. I was in mile two ...