AFAIK, anti-aging science is pretty close to pretty majorly increasing our life-spans if not reversing aging completely. But it will probably cost a lot of money and won't be available to most people for decades.

The best thing you can do right now is probably get regular exercise, eat healthy, and eat in moderate amounts. The more calories you consume (or are required to consume based on your height/weight), the lower your lifespan will be.

Edit: I believe scientists have already cracked a lot of this stuff in mice and so on.