I do not think I am the expert you should consult, but I can tell you where my knowledge base comes from. I have endured a lifetime of people with very exact ideas about health maximization, but with a paucity of data or carefully controlled studies. I thus tend to be skeptical of very specific advice. At the same time, common sense appears to yield some broad dividends, or will involve no real cost. I think the answers that follow are pretty stupid and uninteresting, but this was the highest rated reader request, so here goes:
1. Don't drink. It is fine or even beneficial for most people, but terrible for 10-15% That might be you. And even for those who are not "problem drinkers," I've had plenty of people write me and tell me their lives are much better since they stopped drinking. Stop treating "drinking" as a default.
2. Exercise every day. For me the main options are basketball, tennis, walking, weights, and Peloton. I am not suggesting those are best, they are simply what I bring myself to do. And indeed that is probably the most important factor for you. I am skeptical of very high stress exercises, such as risky rock climbing, and so on. I don't see the case for making your exercise into a health risk.
3. Get good sleep. I am blessed in this regard. For me what works is going to bed and waking up at regular hours, and not treating weekends any differently. I don't pretend that advice has universal validity, but perhaps for some of you it is worth trying. Other people have theories about sleeping in the cold, sleeping with masks, etc. I am not opposed! Try those if you need them. I don't.
4. Don't eat junk food. Try to eat mostly unprocessed foods. That said, I don't think we understand diet very well or have good data on what works. I just don't seem the harm in eating mostly natural foods. They taste better anyway, and there is possible upside.
5. Be happy. Have goals and projects. Have sex. Have good social networks. There is some evidence on these, I am not sure how strongly causal it is. "Go to church" might work as well, but I don't do that one. It would frustrate me more than anything.
6. Unless you have strong evidence to the contrary, take a minimum of medications. Don't just pop random stuff because it might have some modest short-run benefit. But yes I do believe in vaccines and most of all those kinds of medicine that have direct parallels with what we do to try to fix animals.
That is my advice. I consider it mostly trivial, but still it is better than violating the advice.