Ryan Phillippe and his his longtime personal trainer, Happy Hill, refer to the actor’s training regimen as a “prison-style workout” for both its simplicity and reliance on basic equipment: barbells, dumbbells, and bodyweight moves.

Phillippe’s “Happy Hour Grind,” a five-times-weekly, 90-minute workout—which encompasses old-school calisthenics, free weights, and a half-hour warmup of sprints on a treadmill or an elliptical—tests both his muscular endurance and trains his entire body.

Phillippe doesn't just grind through the motions, though—he has the training know-how to adapt on the fly and to turn his surroundings into a gym, whether that means tearing through dips or incline pushups on a rock, or using a boardwalk railing to work on his abdominals. Wherever the 42-year-old Shooter star trains, maintaining his lean, muscular physique requires consistency and a clean diet. “You get half the results for twice the work [as you get older],” Phillippe says. “We’re all going to age, but if you don’t want it to be as devastating as it can be, take care of yourself. Eat right and get to the gym. I’ve never gotten lazy about that.”

How to do it

Perform each circuit three times before moving on to the next. Between circuits jump rope for two to three minutes, alternating between single jumps and double unders. Rest as needed between rounds. Pressed for time? Focus on one circuit for as many rounds as possible.

For more from Ryan Phillippe—plus the latest in looking great and eating right—pick up the June 2017 issue of Men's Fitness on newsstands now.