Leilani and I have self-imposed dietary restrictions. It's an anti-inflammatory diet and it's very low in sugars, carbohydrates and foods with high arachidonic acid.
Before the diet my inherited bursitis was so bad I couldn't walk 2 blocks without sitting and resting and I couldn't drive for more than 15 minutes or so without an ice pack on my hip. Now I walk 4 miles a day with zero pain and driving for hours doesn't bother me at all.
It's worked just as well for a sports injury in my hand where arthritis set in.
It's not an easy diet to follow, but it's better than being in pain or taking drugs which for these conditions have unfortunate side-effects.
I got the diet from a doctor who told me to try it before resorting to anything else and it works.
Notes
PS as a side effect, I never get sick. This year I went off diet when I was in Vienna for a week, ate a bunch of desserts. I must have caught a cold on the plane. A few days later I got a cold that consisted of; one day runny nose, one day mild cough. That was it. I think the last time I caught anything was 15-20 years ago.
I read something in Scientific American a few years ago explaining why, but I really don't remember exactly what it was. It's about some immune system cells that reside in your mucus membranes that inflammatory foods, especially sugars and starches suppress.