Looking at the causes behind mobility issues

DEAR DR. ROACH: I am 79 and can move around without any problem. I walk five days a week, and my weight is normal. However, it seems to me that many people -- some younger than I am -- have mobility problems. I wonder what causes this problem. Is it lack of exercise, genes, weight, etc.? -- E.G.ANSWER: Be very grateful that you can move around without a problem, as most people in their late 70s…