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.
Diagnosis - Forward Head
Your chin looks like it protrudes out from your chest and your legs are in front of your shoulders.
WHERE PAIN STRIKES: Neck
THE PROBLEM: You have weak front neck muscles
FIX IT: Do this neck "crunch" every day: Lying face up on the floor, lift your head so it just clears the floor. Hold for 5 seconds; do 2 or 3 sets of 12 reps daily.
Source: Men's Health