What's awesome/awful about the stairmill is that there's no way to sandbag it. If you go slow, you get a longer concentric action, making your muscles burn, scream for oxygen, and work harder. If you crank up the speed, your heart and lungs have to work double time. Fast or slow, your butt gets burnt.

Just 15-20 minutes 2-3 times per week will really improve your conditioning. And because there's little to no eccentric (negative) action, this won't interfere with leg day.

Too easy? Do this:

• Take two steps at a time.
• Do the whole session without touching the handrails.
• Turn around backward. (You can hang on for this variation.)
• Hold a medicine ball any way you can, or wear a weight vest.
• Do intervals. Try 30 seconds fast, 60 seconds slow and repeat for a set amount of time.

Outside the gym, take the stairs as often as possible. Climbing just eight flights of stairs a day has been shown to lower average early mortality risk by 33 percent. And people who live in a house with stairs are generally leaner than those who don't, even if they do no other forms of formal exercise.

Not only is this a great form of NEPA (non-exercise physical activity), a study in the journal Neurobiology of Aging showed that people who take at least one flight of stairs each day have "younger" brains, defined by having more gray matter, than other folks their age.

A younger brain, a younger looking butt, and the ability to tackle your next EMOM workout without tanking? That's hard to beat.