Being out in the wilderness, as much as I'm able to be, alone always. Hiking, contemplating, thinking and soaking in every potential nook and cranny that my senses allow. I can say without any hesitation that it's single handedly done more for me than most anything else.
Exercise is right up there for me also, have been pretty consistent with it over the last 15-17 years of my life, it's made such huge strides on my life that can't be languaged, it's changed my life in countless areas.
It's funny to me because out've the multitude of things that I've effortlessly chucked aside and never followed through with in my life - it was the one thing that stuck, and not just did 'it stick' ..but it worked. It was the one thing that I could put in the hard work, the crying, the sweat, the pain and immediately [and there-on] feel the 'give back' in terms of benefit, how it made me feel, how I began to relate to the world, myself, and how I handle things in my day to day. And as long as I stuck by it's side and not give up on it or myself - the benefits have continued to compound, continued to grow, year after year.
These two things combined have directed such a huge part of my life, and cured me of a past addiction. They saved my life, literally.
Any I'm not talking for vanity-sake when I talk exercise either, I'm talking mostly in the realm/pursuit of physiological and mental benefit, which honestly ..when you look at all the studies ..it's unparalleled in it's ability to help, heal, and build anew.
If I didn't have these two things in my life as foundational pillars, I'm not sure who/what/where I'd be honestly..
Hope it helps, and best of a journey to you 8)