Learning about one or more health-related aspect. Apply what was learnt over an extended period of time (ideally, to some degree of proficiency or mastery). 
Re-assess overall health / lived experience. Adjust accordingly. 

Health-related activities will change as life situation changes. You may cycle through things that now don’t work, or, now they are actually something you should focus on.

Some specifics:
- From my perspective, most people overlook light health (and over-state their own specific requirements for gut-health).
- Understanding respiration has been a game changer for me (teachings from Erwan LeCorre instead of Wim Hoff).
- Overall mineral/vitamin content of naturally occurring food for where I live (seasonal eating instead of rigidity)
- Marry the disciplines of strength & flexibility in your training (they do not need to be separate).
- Do micro-difficult things often (improves tenacity).