Exercise in early life has long-lasting benefits. The researchers found that bone retains a "Memory" of exercise's effects long after the exercise is ceased, and this bone memory continues to change the way the body metabolizes a high-fat diet. Source 7d.
I'm sure it's never to late to start doing this. The best way is to start small by setting attainable goals. Once you meet those goals a few times reach for something a bit harder. Before you know it you'll be doing things you never thought you would.
I do not buy this research. Too much research as put that every seven years our body has reproduced and replaced the older cells. Thus it why at times a person with no known allergies will suddenly develop allergies or even a different taste of foods they now like instead of what they once did. I feel that the bones in your body retain a memory longer than seven years.