Zen Buddhism. I dabbled with the concepts and played with the idea of taking it seriously for about 15 years before I finally surrendered to the idea and it changed everything.
I became interested through books but ultimately if it’s something you’re interested in pursuing you’d want to find a temple or community and practice with those that have more experience.
Two books I read early on that I recommend are The Tantric Distinction and Zen Mind Beginners Mind.
