I love an exercise you can do anywhere, anytime. I like the ones that require no equipment. This elbow plank [1] has an added kick to it, and I mean that literally. Adding a donkey kick to this move requires extra strength, as it will challenge your core while toning your booty and hamstring. Here's how:

• Begin in an elbow plank with elbows directly under shoulders, abs engaged toward the spine. Don't let the pelvis sag down or pop up.
• Lift right leg off the ground, bending your knee so the sole of your foot is toward the ceiling. Keep pelvis square to the floor. Don't let your pelvis twist.
• Press your right heel towards ceiling as high as you can without moving pelvis or low back. The motion will not be huge, but concentrated on the booty and hamstring.
• Lower the bent leg slightly and repeat for a total of eight to ten repetitions. Then switch sides.
• Do two sets on each leg.

I like to hold a Downward Facing Dog [2] for five long breaths between sets.