The sit-up is a classic for a reason: When done correctly, the deceptively simple move works your abs as well as a bunch of other stabilizing muscles in your hips and pelvis to help you build a coordinated, solid core. That makes everyday activities as well as other exercises like running easier, and prevents injury.

But if you’ve been doing sit-ups since you were a kid, you might be ready for something… more. What if you want to take your sit-up to the next level? A simple way to do that is by grabbing a dumbbell, strength training plate, or heck, even a bottle of wine, for a weighted version of the move.

Adding in a weight is a great way to keep your body continually challenged in a way that builds muscle.

“Making small changes in weight equate to big impacts and results,” Phil Timmons, program manager at Blink Fitness, previously told Well+Good. In the case of the weighted sit-up, you might be moving from bodyweight to just a few pounds, or maybe you’re adding on a heavier load. In either case, “your body wants to become efficient at the demands it’s placed in,” says Timmons. And that drive to become more efficient is what causes muscle growth. Or, in the case of the weighted sit-up, a stronger core.

But the weighted sit-up is trickier than it looks. In the latest installation of The Right Way, trainer Morit Summers will lead you through the most common pitfalls of this challenging move, which include a lot of flailing and breath holding. Make sure to keep your feet on the floor during a sit-up, people! And for gosh sakes, don’t hold your breath. Instead, exhale on the way up so that you’re contracting those muscles when you need ‘em.

And, as always, slow and controlled is the name of the game in this strengthening move. Relying on momentum just wastes your time. That means not letting the force of gravity take you back to earth as you’re coming down from your sit-up, but instead lowering back gradually using the strength of your abs.

Watch Summers take you through the right way to do a weighted sit-up in the video above, and get that core all fired up.