Answer:

Neck pain can be annoying and in the way.  It makes your arms feel weaker, your posture feel 'off,' and your overall mood a bit different.  There's something inside of us that doesn't quite accept neck pain, so our bodies are fighting it off all the time.  Large muscles in the area, like your upper traps, tend to fire like crazy and create a pull that may or may not result in a headache.

The good news is that a slight chin retraction while working out (like you're giving yourself a double chin, but less effortful) will produce an amazing result.  In fact, this is the number one thing you can practice, to relieve both neck pain and potential headaches from improper muscle recruitment:

Chin Retractions:  With tall, erect posture, give yourself a double chin, while pointing chin straight out (never up, error down if anything).  Hold 10 seconds and repeat 3x every day.  

Preferably, until you get the hang of this exercise, watch yourself in the mirror.  If your shoulders rise, your head tilts or turns, or you lose your posture, you're losing the benefit.  Train yourself to be in the posture you desire through exercise, and then superimpose it onto more difficult and dynamic movements, like squats, lunges, and presses.

Align your upper body, release what's tight, and work on posture.  Most neck pain will be resolved this way, but always be sure to check with your doctor and/or physical therapist.  It's very important you have supervision and clearance when dealing with your neck, and be sure to take any radiating symptoms (traveling) seriously.

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