Exercise is always a good thing of course and maybe it would do it for most of us -- not me though, too many joints down to bone on bone, but there are some forms of exercise I could do with my upper body if I could get motivated.
One suggestion Faith is a rowing machine. Most gyms have one and it is a great way to get both a cardio and resistance workout without placing too much strain on lower joints like knees and hips. There are many home versions as well that can be purchased. Another suggestion is swimming exercises. Good for cardio and less strain and impact on joints.
Regarding diets, I know many have already chimed in, but the real key is to focus more on cooking your own food and knowing what you buy. As you stated, try to avoid heavily processed foods and starches. Don't be overly concerned about fat intake; that can be simply mitigated by reducing the consumption of red meat and instead, stick to poultry and fish. Fish especially have the good kinds of fats along with Omega-3s.
From my own perspective, being Greek, I have primarily subsisted on a mediterranean diet which has lots of fruits and vegetables and only uses olive oil for cooking. Although even I like a cheese burger now and again.