Working. Continuous, into the 7th hour without a break and ready for 4 or 5 more, absolutely killing it with 100% precision with 100% efficiency, working. I can't do physical labor like that anymore, but I can damn sure still do it with my hands, eyes, ears, and mind.
When I was processing toxicology data, I would essentially analyze "batches" of 96 patient samples for 56 different compounds each. The average for the most productive lab employees was 5 to 6, while mine was in the low 30s. When I start doing something with such perfect, beautiful automation, that every part of me is doing a task that looks down right robotic, my mind enters some zen state where I can entertain all sorts of thoughts outside of what I am doing, outside of being me, like having a binary brain. I crash hard at the end, and I'm unbearable until the weekend, but I love that feeling. Whether it is polishing metal, shaping acrylic, looking at numbers, taking things apart, walking up hills, finding things in the woods, as long as I can do it with zero to minimal interaction and disruption, I'm perfect.
Sadly, the modern workplace really just isn't set up for this type of work; too many distractions, too much interference, etc. c'est la vie.
That said, it's always been quiet, the woods, solitude, and birding. I've tried all sorts of art; music for years, sculpture, so forth, and their lack of objectivity proves to be pretty stressful for the most part, but those stresses are punctured with some of the greatest highs I've felt.
Oh, and scalding hot outdoor showers.