To boost core strength—without torqueing an old back injury—try our Barbell Rollout exercise, part of the 20-Minute Workout in the February issue of Men’s Fitness. It’s simple. Grab a barbell with 10 lbs. on each end, kneel, and roll forward until your lower back is about to sag. Roll back. Repeat. Best part? This weight workout increases stability for a stronger back and core, preventing further injury. Master this move, and you can push yourself harder during workouts, worry and injury-free.