The ONE exercise you need to be doing -

The ONE exercise you need to be doing

The ONE exercise you need to be doing

If you're still trying to get in shape for summer, you're in luck. Health and fitness experts say you only need to do one exercise -- yes, one! -- to work your entire body, burning fat and building muscle at the same time. Not only that but experts say this exercise can correct dozens of health problems.

We’re talking about the kettlebell swing.

What's so great about it? Fitness expert Felicia Romero said the kettlebell swing works the whole body but is especially beneficial for the posterior chain -- your hamstrings, glutes and back. Like any exercise, you have to do it the right way for it to do any good.

"The kettlebell swing is not a squat," Romero explained. "It's a hinge at the hip."

The other big no-no, according to Romero, is leaning back at the top of the swing.

"A lot of people think they need to swing and squeeze their glutes. You want your core to come into play so as you’re hinging and the kettlebell comes up, you're stopping at that neutral position."

If you think a heavier weight is the key to getting the most out of the kettlebell swing, Romero says think again.

"You don't have to do a crazy amount of weight with this," she said. "I would say work on your form and then work your way up when it comes to the weight."

Romero says you'll know you're doing the exercise incorrectly if you feel it the wrong places the next day or if you feel actual pain in your lower back. She advises three set of 12-15 reps several times per week. Done consistently, you should start seeing changes in your body within a few weeks.

Kettlebells are available in a variety of weights starting at 5 pounds. The one Romero was using is 15 pounds. You can find that weight on for about $20.