FHP (forward head posture) is fairly easy to detect. Have someone look at you from the side.
Look up at the ceiling, down at the floor and straight ahead. Then have
the person draw an imaginary line up through the shoulder. The line
should extend up through the hole of the ear. Ideally the head should
sit on top of the shoulders like a golf ball sits on a tee. Remember
for every inch your head is forward past that imaginary line you are
adding approximately10 lbs. of weight to your spine.