Avoid chronic inflammation like the plague:
Chronic inflammation is a pathological condition characterized by continued active inflammation response and tissue destruction. ... chronic inflammation can be a major cause of cancers and express aging processes.
Moreover, many studies suggest that chronic inflammation could have a serious role in wide variety of age-related diseases including diabetes, cardiovascular and autoimmune diseases. The inflammatory process induces oxidative stress and reduces cellular antioxidant capacity. Overproduced free radicals react with cell membrane fatty acids and proteins impairing their function permanently. In addition, free radicals can lead to mutation and DNA damage that can be a predisposing factor for cancer and age-related disorders.
As I've noted in the past, the best short term way of evading chronic inflammation, and thereby increasing your chances to living more healthy years, is to avoid carrying excess visceral fat. But that only gets you so far: eventually even the healthiest immune system in the healthiest body starts to fall into a permanent condition of chronic inflammation called inflammaging. Evolution didn't produce a system that can be used for as long as we modern humans would like:
Inflammation is necessary to cope with damaging agents and is crucial for survival, particularly to cope with acute inflammation during our reproductive years. But chronic exposure to a variety of antigens, especially to some viruses such as cytomegalovirus, for a period much longer than that predicted by evolution, induces a chronic low-grade inflammatory status that contributes to age-associated morbidity and mortality. This condition carries the proposed name "inflammaging". Centenarians are unique in that, despite high levels of pro-inflammatory markers, they also exhibit anti-inflammatory markers that may delay disease onset. The key to successful aging and longevity is to decrease chronic inflammation without compromising an acute response when exposed to pathogens.
So when I say "avoid chronic inflammation" I'm not really talking about sane lifestyle choices, although that's very necessary as well. I really mean "do what you can to help advance medical research into repairing our aged immune systems." As time goes by, you'll find that the greatest determinant of your health and longevity is medical technology that can repair the damage of aging. While we're healthy and active, we should do what we can to advance that medical research; it'll pay off later.