Forward head posture can have ill effect through out the body, from the upper cervicals, to the plantar fascia.
Here are a few simple movements you can use during the day to assist in pulling the head back.

Strengthen Deep Neck Flexors (Img. 1)
Drape a resistance band over the base of the skull, just above the ears. Find a comfortable place to hold each end of the band. The closer to the body you hold, the more resistance you will feel when preforming elbow extensions.
As seen in image 1 above, perform elbow extensions, slowly. Come slowly back to a start point, ending with elbows flexed. By completing this movement you must contract the deep head/neck flexors, longus capitus and longus coli, in order to keep the head from flopping forward. You may experience an ‘opening up’ of tissue at the cranial base, the occipitoatlantal joint, and a release of tight tissue in the back of the neck. Repeat a few times a day, start with sets of 5, then 8 and so on. Be sure to maintain proper breathing during this movement.

Deep Neck Flexors (Img.2)
Image 2 is the same movement cue without the resistance band, and is easier to do while driving to work, sitting at the computer, or on the dance floor. In the image I use my finger as a guide, not a force pushing on the chin. Simply glide the cranium posterior, keep the eyes looking forward. Many people will have a tendency to look up toward the sky a bit. The point is to open the posterior cervicals and strengthen the anterior, deep head/neck flexors.
These simple techniques can ease neck, shoulder & upper back pain and may help reduce the formation of Dowager’s Hump at the base of the neck/upper back.