Lie on your back on the floor or on a yoga mat. Double-up the exercise tube and place it over your hips, holding the tube against the floor with your hands.
Exhale and push into your heels to lift your buttocks off of the floor. Keep your core engaged at all times and avoid overarching your low back and also avoid shrugging your shoulders. Inhale and slowly lower your buttocks back to the floor, trying to keep your glutes engaged the whole way down.
Repeat 8-12 times, rest, then repeat the entire exercise if desired.