There are a large number of exercises you can do do get your butt/glutes firmer. You won't lose the shape when you do these exercises. As a matter of fact, you will improve it.
1. Squats - can be done with or without weight. You can even use milk jugs full of water for resistance. Hold them at your sides and squat down until your thighs are parallel to the ground.
2. Lunges - this is one of the best exercises for firming up your rear end and can be done anywhere.
3. Dumbbell Split Squats - these look very similar to Lunges only you don't step forward and back, you keep your feet in the same position and move your body up and down while in a lunge position.
4. Glute extensions - this is done using an ankle harness and a low pulley in a gym. Stand facing the cable machine with the harness on your ankle. Keeping your leg stiff and straight, extend your leg back behind you.
5. Butt blaster - a glute extension machine found in some gyms. You are basically pushing up with your foot against resistance while you are on all fours (threes actually, in this case). It looks like a horse kicking back and up.
6. Glute push-ups - lie flat on your back with your knees bent 90 degrees and your feet flat on the floor. Using your glutes, push your hips up towards the ceiling and squeeze hard.
|The 4 Most Insane Bodyweight Exercises I've Ever Done|
|How to Spot Reduce Stomach Fat|
|The Great Big List of Calorie-Free Foods|
|16 Tips and Tricks For a Bigger, Better Squat|
And see every new exercise and training technique the moment I load it up!