Here’s one of my favorite ab moves that has stood the test of time in my arsenal of abdominal exercises. I first learned this in kickboxing back in college, but it works so well that I still do it today.

Start with your feet flat on the floor and lean back until you start to feel your abs working. Punch your right fist toward your left knee as you twist slightly to the left. Reverse to punch your left fist toward your right knee as you twist slightly to the right. Repeat 12 times. Do three sets. You’ll work your entire core, especially your obliques.

For an added burn, lift you feet off the ground so you’re balancing on your sit bones. Pick up your pace to double time–twist and punch left to right until you have to stop.

Have you ever wondered what you’re supposed to do with those foam rollers in the gym? For one, you can use one to give yourself a massage. If your muscles are tight, say your quads, you can lie on the foam roller and slowly roll your body back and forth along the roller to work out the kinks. When you get to a knot, you can stay put until the pressure eases and then continue rolling.

But if your muscles are feeling fine, you can use rollers to add instability and variety to strength building moves. Here are a couple ideas from Diet.com.

I took a new class the other day that incorporated the Body Wedge–basically it was sculpt on an angle. The Wedge is like an incline bench except it’s made out of soft foam material which adds a challenging level of instability (and it’s more comfy to lay on!). With it, you can work pretty much every muscle in your body (back, butt, triceps, shoulders, etc.)

During the class we stood and sat on the wedge, lifting weight with dumbbells and body bars. We also laid on it for ab work. If you’ve ever done ab exercises on the incline bench after months of doing crunches on the ground or tried lifting weights while standing on the Bosu, you’ll know what I mean when I say the extra incline and instability really helps you feel the burn!

The Wedge didn’t seem like a dramatically different fitness tool, but it will work your muscles in different ways, so try it the next time you want to mix up your strength routine.

Here’s a move from Women’s Health that I tried the other day. The added weight will definitely have you feelin’ the burn. This move works not only your abs, but also your hips and upper back.

Start lying on your back with a set of 10- to 12- pound free weights.

Raise your legs to a 45-degree angle with your arms over your head to get to the starting position shown in image A.

At the same time, lift your legs until they’re perpendicular to the floor and reach your arms over your chest and toward your toes, lifting your shoulders off the floor.

Return to the start, never letting your legs touch the floor and continue for 3 sets of 15 reps.

Teaming up with a partner can make your ab workout more fun. Grab a medicine ball and try these two core building moves made for two.