12. Full push-ups
Engaging your glutes can help keep the lower back from arching or sagging. Once you have completed 15 reps comfortably, move up to two sets with a 30-second rest in between.
STEPS:
1. Get into a high plank position with your hands directly under shoulders.
2. Begin to lower your body—keeping your back flat—until your chest grazes the floor.
3. Keeping your core engaged, exhale as you push back to the starting position.