Tighten Your Butt

You can do it all in just 15 minutes.
One-sided relationships are rarely healthy—unless you're talking about unilateral training. Supporting weight on just one side of your body at a time offers benefits that evenly loaded strength-building moves inevitably miss.
"When you work each side independently, you're able to laser in on just those muscles, so you can perfect your technique, spot weaknesses, and really control each rep," says certified strength and conditioning specialist Mike Robertson, president of Robertson Training Systems in Indianapolis.
And while your legs, butt, shoulders, and back are the main stars of this routine, they're not the only ones being challenged. "Your core is working twice as hard to correct a rotational pull from the weighed-down side," says Robertson, who created the workout here.
Two or three times a week, complete this circuit using a kettlebell ("It allows for a more natural hold than a dumbbell," says Robertson). Begin with the first exercise and rest for 30 seconds before moving on to the next. Repeat two times for a total of three rounds.