Neck Lie on the floor, on your back, with a pad or cushion under your head. Now make a wrestler's bridge.
Only your feet (or toes) and head should be in contact with the floor. Roll your body side-to-side and touch each ear to the floor, while staying in the bridge. "Roll" around while in the bridge, letting various parts of your head to make contact with the floor. Lower your bridge until your back brushes the floor, and then go back into a full bridge. Do all these exercises slowly. Don't let your body "drop." Lower it slowly. Do this for about 10-15 minutes daily, taking one day off a week. After a while, when you notice your neck getting stronger (and bigger), add some weights to your chest, holding them in place with your hands. Eventually, you will be able to do this while supporting another person. When I wrestled, not only could I support the heavyweight on our team (who outweighed me by about 120 pounds), but no one could "break" my bridge.
ShouldersStand upright, with your arms at your sides, holding a full gallon of milk (or whatever) in each hand. Alternately, try to touch each shoulder to the corresponding ear, but keep your head straight. Don't move your head, move your shoulder. Just about the only part of your body that moves should be your shoulders, one at a time. Don't rock back and forth to make it easier, don't bend to the side, and don't swing the bottles. Do each side 10 times the first day, and increase the number as you can. When you start taking too much time, increase the weight.
Still holding the bottles at your side, slowly raise each arm (separately) to the front, and slowly lower it. Start with 10 times with each arm, and increase as you can. Now do the same thing, but to each side. At neither time, to the front or to the side, should you swing the weights. That would defeat what you are trying to do. It isn't a contest.
In the same position as the shoulder work above, slowly shrug both shoulders. Do this 10-20 times. Now, still standing still and holding the bottles, rotate or "roll" each shoulder forward and back. Do this 6 days a week as well. As it becomes easier, increase the weight.
At this point, you may have to buy a pair of dumbbells. A plastic gallon of milk or water weighs just a bit over 8 pounds, so you will need to judge for yourself how much to increase the weight.
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Don't expect results overnight. If you allow your body time to adjust to this, you will see your strength improve within 2 or 3 weeks, and continue to improve as long as you keep challenging your muscles. You may have some bad days, and some days when you just can't lift as much as you were lifting. Take a few days off, then start back up.