I mostly run on roads, but far prefer packed dirt trails. Roads are the easiest, but trails are much more forgiving on your legs. One thing I would suggest is to take a look at your shoes and see how they are wearing. If you are just now starting to develop little aches and pains new shoes might take care of that. If you can see the midsole through any part of the outsole or see wrinkling in the foam, that's an indication that they are wearing out. Another thing to mention is that asphalt is actually softer than concrete, enough to actually make a difference. So if you are able to run on the road instead of the sidewalk without getting run over, that could even help a bit too. But finding some nice groomed trails will increase the quality of your life, by far!!