Image courtesy of Men's Health

Nothing says "fit" like a wash-board stomach. And nothing makes achieving one harder than doing the same exercises every week. "Your body adapts and stops responding to exercises over time, stalling your progress," says Bill Hartman, C.S.C.S., co-owner of Indianapolis Fitness and Sports Training. That's why it's important to regularly hit the refresh button on your ab routine. "Adding different exercises to your workouts gives your muscles a new stimulus and triggers growth," says Hartman. The result: head-turning abs in significantly less time.

But attracting more attention at the beach -- and in the bedroom -- isn't the only reason to pursue a chiseled midsection. "A strong core helps you maintain the optimal alignment of your pelvis and torso in everything you do, whether you're going big at the gym or carrying a cooler across a campsite," says Hartman. "If you can't maintain that alignment -- characterized by a natural S-curve in your spine -- your joints are thrown out of whack, increasing your risk of injury and limiting the amount of weight you can lift."

This summer, take a break from your usual ab exercises and weave two of the moves on the following page into each of your weekly workouts. Which two you pick doesn't matter as long as you choose a different pair each time. Then prepare yourself for the result: a six-pack that goes everywhere you do.

Challenging your body in new ways hits your muscles at different angles, packing on size. For all-new exercises from Men's Health experts, subscribe to our Exercise of the Week newsletter.

1. Kettlebell Pullover

How to do it: Lie on your back and raise your legs. Bend your knees 90 degrees and spread them apart while keeping the bottoms of your feet together. Lift a kettlebell straight above your head, holding the sides of the handle in both hands. Lower the weight behind you, stopping a foot off the floor. Hold for 30 seconds, and lift it back above your head. That's 1 rep. Do 5.

Why it works: "Pulling things overhead while lying on your back is what you did when you were a baby," says Hartman. "It's a natural movement that perfectly aligns your extremities and loads your trunk, activating and strengthening your core."

2. Plank Cable Row

How to do it: Attach a handle to the low pulley of a cable station and face it in a plank position, resting your weight on your forearms. Grab the handle in your right hand with your arm outstretched. This is the starting position. Pull the handle toward your right side, stopping when your elbow touches your ribs. Return to the starting position. Do 3 sets of 10 reps per arm.

Why it works: "Pulling weight toward you in a plank engages your lats, abs, and obliques," says Tony Gentilcore, C.S.C.S., a trainer at Cressey Performance in Massachusetts. "That not only rocks your core and boosts torso stability but also helps you build a better-looking back."

Protect your back my mastering your form on this exercise. Click here to see trainer David Jack teach you The Best Way to Do a Barbell Row.