Boost a flat butt
To give your behind more curves, you need to develop the gluteal muscles. You can do this by performing strength moves that target the butt and thighs. Try these exercises at least two times a week, taking a day of rest in between. In eight to twelve weeks you should notice your rear getting firmer and curvier.
Squat
Stand with your feet shoulder width apart, toes pointing forward and hands on your hips. Squat by lowering your hips and pushing your butt out behind you. Keeping your back at a diagonal. Lower your body until your knees bend to about 90 degrees, and keep them over your ankles, not toes.
Squeeze your butt to stand up straight and repeat. Do two sets of 15 reps.
Once you are comfortable with the move, hold a 5 to 8 pound dumbbell in each hand and hang your arms by your sides. You may need to start with fewer sets and reps; work up to three sets of 12 reps.
Safety: if your back feels strained, make sure you are not bending too far forward. Lean at a diagonal from your shoulders to hips, holding your chest above your waist to avoid bending over too far. If your knees feel strained, push your hips farther back and make sure you hold your body weight in your heels, not toes, al all times during the squat.
Back Lunge
Stand with your feet hip width apart, holding a 3 to 10 pound dumbbell in each hand, arms by your sides, palms facing in. Lunge back with your left leg. As your leg steps back, land on your toe and keep the back heel raised. Lower your body until your front knee is bent 90 degrees. Make sure your calf is perpendicular to the floor, not slanted.
As you exhale, return the back leg to the front and straighten both legs to return to standing. Inhale as you slowly lower and repeat, alternating legs. Do three sets of 12 on each leg.
Safety: When lunging, if your back knee feels strained, reach farther back with your back foot to straighten your leg more. If your front knee feels strained, make sure that your feet are wide enough apart that the body weight is distributed between your front heel and back toe, rather than front toe.
Doggy raise
Begin on your forearms and knees, head facedown. (Place a mat or towel underneath your knees for extra cushioning) use 3 to 5 pound ankle weights or squeeze a 3 to 5 pound dumbbell in between your calf and thigh. Cross your left leg over your right calf so that your left knee is resting on your right calf.
As you exhale, squeeze your glutes and uncross your right leg to raise your right thigh, stopping when your knee reaches hip level. Keep your belly button pulled in to stabilize the torso. Keep both hip bones level and parallel. Hold for one second then slowly lower the raised leg to the starting position. Repeat slowly, do two sets 12 times, then switch legs.
Safety: Avoid arching your back or tilting your hips sideways as your thigh rises. Keep your torso stable throughout.

