4. Plank
Begin with your body supported on your elbows (or hands) and toes. Do not let your back or legs sag or arch. Hold for 30 seconds, 2-3 times. Try different plank variations: first on hands, then elbows, then side plank. Each session should last at least 2 minutes. Do not perform if you have had recent surgery, tendon problems, organ inflammation, or heart or blood vessel issues.