SINGLE-LEG GLUTE BRIDGE
Start by lying on your back, arms by your side, with your feet planted on the ground. Lift your left foot and straighten your leg (a). Pressing through the heel of your right foot, lift your hips off the ground, and squeeze the glute at the top (b). Try to get your hips, knees, and shoulders in one straight line. Keep your abs engaged and your glutes squeezing the whole time to prevent your lower back from dropping. Do 15 repetitions on this side, then switch to the other leg.