A long lifespan is great, but only if you're healthy enough to enjoy it. So how does one expand one's "health span"? This is the central theme in Bill Gifford's book, Spring Chicken: Stay Young Forever.
Gifford explores this topic with a completely open mind. No conventionally believed piece of wisdom is too taboo to contradict. But he also recognizes that there is way more that we don't know than what we do. As such, we can't really be sure of too much. We are only scratching the surface of what makes our bodies age and how to counteract that, which is bad news for those of us who are already decades old.
As such, there is no checklist at the beginning (or the end) that tells you exactly what to do. About one recommendation is buried within the narratives that make up each chapter. Some of them won't surprise you (exercise is good, sugar is bad) while some might (cold showers and skipping meals are likely good), depending on how much you are already familiar with this subject matter.
If you want a practical guide that tells you what you should be doing, I'd stick to Tim Feriss' The 4 Hour Body instead. But if you want to get a little deeper into the science and the narratives of how the latest current thinking has come to the forefront, then Spring Chicken: Stay Young Forever (or Die Trying) is probably the better bet. Good luck in getting healthier!