Eat healthy. exercise. avoid smoking. why did i get arthritis?

Bad luck, bad genes: There is much in life that is out of our control. Genetics and luck do play some role. All we can do is to to improve our chances for achieving what we want out of life. A good diet and exercises still helps in a myriad of other things from mental health to other parts of physiologic health. Flexibility and low impact exercise is helpful with arthritis so keep it up!

Not your fault: Most types of arthritis are not directly related to diet, exercise or smoking. Sorry for your bad luck but your habits put you in a better place to deal with the disease.