Crick in my neck

WHAT is it that leads to a crick in your neck anyway? Is it built up stress? Sleeping "incorrectly"? All I know is that it makes me feel really old and out of shape, which I am, and
grouchy bunny-ish! Hate feeling like there is something between me and the world at large. Just makes me think about how good you have it when, in general, you have your health. Even people my age are dealing with ailments that I cannot imagine at this stage of life, always having MRIs and other very serious sounding tests. I think I would fear dying every day if I lived with any REAL problems. Thank...somebody that Im healthy and its only my mind that I need to conquer...today.