Bust out of your booty training rut and tone your glutes fast with a speedy 12-minute workout.

Whether you want to rock a pair of skinny jeans or a teeny competition bikini, you’ve got to light a fire under your butt, so to speak, with each workout. The good news: Adding two common fitness tools – dumbbells and a stability ball – to your regular exercise mix may be the key to shaking up your workout and getting the rear-view you deserve.

Strength stalemate Bodyweight moves, like squats and lunges, are only effective to a point. Your legs and glutes are used to holding your body up and moving it around all day, says Christopher Mohr, PhD, RD, an exercise physiologist and owner of Mohr Results, Inc. in Louisville, Kentucky. These traditional upright bodyweight exercises may not be pushing your muscles to their maximum workload because your body has adapted to these actions, and that can mean disappointing results for you.

So what is the secret to great glutes? Continually challenging them, says Michele Olson, PhD, CSCS, professor of exercise science at Auburn University at Montgomery, Alabama and creator of the DVD Fitness Prescription: Perfect Legs, Glutes & Abs. “Once your glutes get used to your body weight, they can no longer improve beyond that point unless you add more load,” she says. The added weight of dumbbells instantly shocks muscles into working at a higher level, and balancing on a stability ball delivers leverage and intensity that’s hard to achieve by doing the same moves without it.”

Adding dumbbells to traditional body weight exercises, like lunges and squats, provides multiple benefits. Dumbbells help you develop firmer, rounder glutes by increasing the intensity in moves you love but no longer feel are challenging to you. And in order to see results, you must resist grabbing what you would use for hammer curls and kickbacks. “Compare the large gluteus maximus to, say, the size of your triceps, and you can easily see why you have to have a greater load,” says Olson.

Try using any weight that you can safely lift off the racks and carry with your arms by your sides to start. Throwing a stability ball into the mix keeps your posture well aligned during standing moves like wall squats. And incorporating the ball into isolated, floor exercises instantly jacks up the intensity while recruiting additional stabilising muscles in your lower body. “It’s much easier to do a bridge, for example, when your feet are on a stable surface like the floor,” notes Mohr. “Move them to a stability ball and you’ve got a completely new move.”

This workout is designed to blast your gluteus maximus and the surrounding gluteal muscles while pulling you out of that butt-training rut. These fresh moves are done with a couple of inexpensive but time-tested fitness tools, and will raise your motivation along with your behind. For best results, do this exercise two to three times per week. Incorporate just the stability ball at first, and once you’ve mastered that, add dumbbells where applicable. Stick to the plan and you can say hello to a firmer behind in four weeks!