I can understand wanting to live a healthier life ... the best advice I can give is to maintain a healthy weight as it impacts so many other facets of your life. My second piece of advice is to get a dog that needs to be walked 2-4 miles a day - it is the absolute end of excuses.

I'm not sure why you'd want to live longer - I'm hoping to go out like my grandfather did. He was never sick a day in his life but had a massive heart-attack in his sleep and never woke up. Living longer might be a side-effect of living healthier and that's fine by me. But living longer while being decimated by the common diseases of those over 80 is not for me.