You may not have heard the phrase, “Stand up straight!” since you were a kid. But whoever said it was watching your back: bad posture can lead to back, neck, and shoulder pain. If you’re already feeling the pinch from years of slumping, today may be a good day to begin a posture challenge like the one covered in TIME. The three-week program was created to help retrain your body, change posture-sabotaging habits, and give you the core strength needed to help straighten you out for good.

Week one: Regain your posture.

• Stand tall. When standing, evenly distribute your weight between both legs. Keep your feet parallel under your hips with your shoulder blades pulled down and back. Also, keep your pelvis stable and untucked by engaging your glutes and core.
• Give yourself sit-support. Line your ears up with your shoulders and your shoulders with your hips; your lumbar spine (lower back) should be slightly curved. Uncross your legs, keep your feet flat on the floor, and press your lower back into your chair. If your lower back doesn’t touch the chair, add a lumbar pillow or rolled-up towel.
• Take a spine-friendly snooze. Sleep on your back or side to help neutralize your spine.

Week two: Send bad habits packing.

• Share the load. When carrying a heavy bag, switch it to the opposite shoulder every ten minutes to give each side a break.
• Stop the text neck. Glued to your phone? Hold it closer to eye level to keep your neck straighter and reduce the urge to slouch.
• Ditch the stilettos. But if you can’t part with your favorite heels, get off your feet every two hours to reduce stress on your lower back.

Week three: Increase strength and alignment.

• Strengthen your shoulders. This is a great exercise to do while sitting in the office: pull your shoulders down, then back and hold for two to three seconds. Repeat four to five times every 30 minutes.
• Take time to breathe. Lie facedown and put a firm pillow under your abdomen. Take long, deep breaths for a couple of minutes.
• Schedule squats. Stand tall (use your skills from week one!) with your feet slightly wider than hip-width. Keeping your spine straight, lower into a squat, and raise your arms over your head with your palms turned backward to engage your upper back. Do as many squats as you can, aiming to hold each one for 30 to 60 seconds

Source: TIME