How to Stop Neck Cracking
To stop cracking your neck, start by gently stretching your neck muscles 3-5 times a day, since stretching can reduce some of the tension and discomfort that makes you want to crack your neck. Additionally, move your neck up and down, side to side, and in circles to loosen your joints. You should also avoid sleeping on your stomach, which can cause your head and neck to twist in uncomfortable ways. Instead, try sleeping on your side with your knees slightly bent and your arms below the level of your head and hips.
Stretch your neck muscles. Tight neck muscles is a reason some people try to crack their neck, likely in efforts to reduce the tension and discomfort they feel. Instead of trying to constantly release the joints of your cervical spine, gently stretch your neck muscles, which might alleviate your neck issue and eliminate the urge to crack it. Use slow, steady movements and take deep breaths during your stretches. In general, hold stretches for about 30 seconds and repeat 3-5x daily. Stretching directly after a warm shower or the application of moist heat is recommended because your neck muscles will be more pliable. While standing, reach around your back with your right arm and grab a little above your left wrist. Gently pull on your left wrist while laterally flexing your neck in the opposite direction, such that your right ear approaches your right shoulder. Hold for 30 seconds, then do the other side. Mobilize your neck in all directions. If your neck is stiff and has poor range of motion, then maybe the problem is more joint related. In this case, trying to crack (or unjam) your neck joints is certainly warranted, but typically the stiffest joints don't release with self manipulation. Instead, the joints above and below the stiffest joint keep cracking, which may make them a little too loose (hypermobile) and unstable over time. Start with moving your head in circles, first clockwise and then counterclockwise, for about 5-10 minutes each way. You may hear some clicks, cracks and pops in your neck, but focus on the movement and not the sounds. Target the main movements of your neck: forward flexion (looking down at your toes), lateral flexion (ear towards your shoulders) and extension (looking up towards the sky). Go as far as you can in each of the four directions about 10x daily. After a week or two, you should notice an increase in range of motion, which might negate the desire to constantly crack your neck. Strengthen your neck muscles. Strengthening the muscles of the neck is good for stability. Muscles are not only for movement, but they are also important for providing protection and stability to the bones and joints that lay underneath them. Weak neck muscles increase the amount of instability in the cervical spine, which might trigger the desire to crack the spinal joints. Consequently, strengthening the cervical muscles may diminish the desire to crack them. Tie an elastic exercise band around your head and attach it to something stable that's at the level of your head. Walk a few steps away from it until you feel tension in the exercise band. Then do the four main neck movements (flexion, extension, right / left lateral flexion) under tension 10x each on a daily basis. After a week or so, change to a thicker exercise band with more tension. Alternatively, see a physical therapist, who can show you specific and tailored stretches and strengthening exercises for your neck. Examine your sleeping situation. Your neck may not feel right because your sleeping environment may not be suited to your body. Mattresses that are too soft or pillows that are too thick may contribute to neck and upper back issues. Avoid sleeping on your stomach as it can cause your head and neck to twist in ways that irritate the joints and muscles of the cervical spine. Try sleeping on your side with your arms below the level of your head and your hips and knees slightly flexed (the fetal position). Try using an orthopedic pillow, which is designed to support the natural curves of your neck. Alter your work environment. Neck problems are often caused by repetitive motions at work or minor injuries related to physical activity. If your problem is work related, then talk to your boss about switching to a different activity or altering your work station. Maybe your computer is positioned such that it's straining your neck. If so, position it directly in front of you and at eye level. Instead of constantly cradling your phone to your ear and kinking your neck, use the speaker-phone function. If your job involves lots of driving, change the position of your seat backing such that your head can rest comfortably against the headrest, which will reduce the tension in your neck. Change your workout routine. Maybe your neck issue is related to exercising at the gym or at home. As such, take a break from the causative activity (if you can identify it) for a few days and allow your neck to recuperate. Furthermore, you may be working out too aggressively (either too much weight or repetition) or with bad form—consult with a personal trainer, if you're unsure. Positioning the weighted bar on the base of your neck while doing squats can cause cervical joint sprains. Using your head as leverage while doing abdominal crunches can lead to a strain or sprain in your neck. Over the head movements like military press exercises can also lead to neck discomfort. See a chiropractor or osteopath. Chiropractors and osteopaths are spinal specialists who focus on establishing normal motion and function in the neck, back and peripheral joints. Manual joint manipulation, also called an adjustment, can be used to unjam stiff joints or reposition neck joints that are slightly misaligned. It may seem odd that getting a chiropractor to crack your neck may stop you from cracking your own neck, but releasing the stiffest joint(s) instead of the most hyper-mobile ones might cure you of your habit. Although a single neck adjustment can sometimes completely relieve your neck issue, more than likely it will take a few treatments to notice significant results. Chiropractors and osteopaths may also use other therapies for your neck issue, such as traction or massage techniques. Make sure to see a reputable chiropractor or osteopath. Get a professional neck massage. Your desire to crack your neck may be tied to an underlying muscle strain, perhaps from an old sports injury or motor vehicle accident. A deep tissue massage is helpful for mild-to-moderate strains because it reduces muscle spasm, combats inflammation and promotes relaxation. Start with a 30 minute massage, focusing on your neck and shoulder areas. Allow the therapist to go as deep as you can tolerate without wincing. Don't over do it - a light massage may be your best option. Always drink lots of water immediately following a massage in order to flush out inflammatory by-products, lactic acid and toxins from your body. Failure to do so might cause a headache or mild nausea. Consider acupuncture. Acupuncture involves sticking very thin needles into specific energy points within the skin / muscle in efforts to reduce tension, discomfort and swelling. Acupuncture can be effective for a variety of neck issues, which may in-turn impact your desire to crack it. Acupuncture points that may provide relief to your neck issue are not all located near where you feel the discomfort—some can be located in distant areas of the body. Acupuncture is practiced by a variety of health professionals including some physicians, chiropractors, naturopaths, physical therapists and massage therapists. Acupuncture may be used as an auxiliary treatment. See your family doctor. The habit of cracking your neck may be due to a serious underlying medical condition such as arthritis, osteoporosis, cancer or a structural deformity. Degenerative conditions of the neck often cause creaking and cracking sounds with all heads movements. In reality, these are not likely causes for your neck cracking habit, but if all other methods fail to get you to stop, then more serious problems need to be considered. X-rays, bone scans, MRI and CT scans are modalities that physicians may use to help diagnose your possible neck issue. Your doctor may also send you for a blood test to rule out rheumatoid arthritis or a spinal infection such as meningitis. If you are female, you are at risk for cervical subluxation with rheumatoid arthritis. A neck x-ray will be needed before general surgery to rule out this condition. Airway and neck assessment is crucial with cervical subluxation because of the potential risk of spinal cord damage. If no physical issues exist in your neck, then your doctor may refer you to a mental health professional in order to explore any psychological issues. Psychologists sometimes use hypnosis to break unwanted habits. 
Stretch your neck muscles. Mobilize your neck in all directions. Strengthen your neck muscles. Examine your sleeping situation. Alter your work environment. Change your workout routine. See a chiropractor or osteopath. Get a professional neck massage. Consider acupuncture. See your family doctor. 