Strip down to a pair of shorts and have a friend take to full-body photos, one from the front and one from the side.
Keeping your muscles relaxed, stand as tall as you can, with your feet hip width apart. Now analyze your photos to diagnose your posture problems. (Compare to the above images.)
Diagnosis: ELEVATED SHOULDER
Your shoulders are not in line with your collar bone but encroach up toward your ears.
WHERE PAIN STRIKES: Neck and shoulders.
THE PROBLEM: A shortened trapezius (the muscle that starts at the back of your neck and runs across your upper back)
FIX IT: Perform an upper-trap stretch. With your higher side arm behind your back, tilt your head away from your elevated side until you feel the stretch in your upper trapezius. Apply slight pressure with your free hand on your stretched muscle. Hold for 30 seconds; repeat the move 3 times.
THE PROBLEM: A weak serratus anterior, the muscle just under your pectoral muscles running from your upper ribs to your shoulder blades.
FIX IT: Try chair shrugs. Sit upright in a chair with your hands next to your hips, palms down on the seat, and arms straight. Without moving your arms, push down on the chair until your hips lift off the seat and your torso rises. Hold for 5 seconds. That's 1 rep. Do 2-3 sets of 12 daily.
Diagnosis: ROUNDED SHOULDERS
Your shoulders are in front of your hips and ankles instead of in alignment with them.
WHERE PAIN STRIKES: Neck, shoulders, or back
THE PROBLEM: Tight pectoral muscles
FIX IT: Try a simple doorway stretch: Place each forearm against either side of a doorjamb with your elbow bent to 90 degrees. Step through the doorway until you feel the stretch in your chest and the fronts of your shoulders. Hold for 30 seconds. That's 1 set. Do 4 sets daily.
THE PROBLEM: Weakness in the middle and lower parts of your trapezius muscles
FIX IT: Use the floor L raise: Lying facedown on the floor, place each arm at a 90 degree angle in the high five position - that is, your shoulders, palms, and forearms should all be touching the floor. Without changing your elbow angle, raise both arms by pulling your shoulders back and squeezing your shoulder blades. Hold for 5 seconds. Do 2-3 sets of 12 reps daily.
Source: Men's Health - Continuation in tomorrow's health tip.