There are several things that happen when the mechanics are not correct for an extended length of time.
First, without the proper mechanics, that is the structures being where they are meant to be so they move correctly one upon another, they tend to wear out quickly. If you're old enough to remember the old stick shift cars and how missing a shift would make the gears grind, it's the exact same mechanism.
The cervical spine is supposed to have a slight forward curve to it. When that curve is lost the mechanics are NOT correct and the joints will wear out quicker. Plus the geometry of the muscle attachments is wrong so it takes more energy to do even normal movement. Plus, the discs between the vertebra are at risk of bulging back into the spinal cord or cervical nerves and I can guaratee you don't want to go there.
If not corrected the human body will attempt to strengthen the weak mechanics with extra calcium. Thus, the onset of what you would understand to be arthritis. It's not really arthritis it's the bodies attempt to strengthen weak mechanics.
If you let this situation go long enough the opening between the vertebra where the nerve passes from the spinal cord will start to narrow and you've got a full blown pinched nerve. Or the disc will wear out and collapse and either interfer with the Spnial cord itself or one of the nerves passing through from the cord out the cervical opening to the hands and upper body. Again I can guarantee you don't want to go there.
If you've only had the problem for three years it shouldn't take that long to fix. A general rule is one month for every year. But yeah, you should be a bit nervous - it's important.
Once corrected it's very easy to stay mechanically correct. Get in the habit of looking down your nose at people. Pretend you're a snob. No, not really, But do get into the habit of keeping your chin up. Most of what we do in life requires we look down. Well, every now and then throughout the day get you chin up and move your head side to side. Never stretch your neck the other way putting your chin toward your chest. Always look up.
If you've had a stiff neck for three years you're just asking for trouble. Get it corrected now and it'll save you a lifetime of misery. Print a copy of this and take it to your chiropractor. Doc