This is JMHO.
There's an exercise that I do which I know has helped me. Kissing the ceiling. Yep.
Bring your head up to the ceiling and kiss it stretching your lips as much as you can (you'll feel your chin and neck pull) do this
SLOWLY!!!! as you don't want to hurt your neck. Then lower your chin back down and repeat. Do this as much as you can a few times a day.... you can do it anywhere, like watching TV, sitting on the toilet

just don't do it while your driving lol.
Also turn your head to the right and do a few and turn your head to the left and do a few, so you are stretching all sides of our neck/chin (remember slowly, don't hurt yourself).
Does this make sense ???
Well in any case, I believe it helped me.