Yes, thought-provocation and weight-lifting, similar to what you said. It's endorphins and perhaps dopamine, I'm not sure why it happens. The endorphin article on Wikipedia mentions a German study on runners' high.
Learning something awesome
Finally understanding something when it befuddled you a minute before
Reading something really interesting and/or exciting
Getting carried away with certain thoughts
Music I particularly like that has a certain message in it that I agree with
- good music (the making of, the peaks & piques of, the live osmotic absorption of, listening to, dancing [flailing] to, running to)
- stargazing on a blanket in the yard
- rare first-edition signed books in locked glass cases
- the smell of those books
- that part at a party or nondescript social engagement when everybody goes home
- watching dexter, woody allen films, and charlie kaufman films
- the luxury of sleeping enough to remember my dreams
- neck massages, lately
- stabbing hobos
I don't think it's comparable. I don't become relax after fulfilling my required INTP duties, I become more excited. However, after a longer and intenser run (or returning from a break from running), my body feels profoundly relaxed. I drive/stroll below the speed limit vs. the accepted/expected speed limit + 5 mph, my ability to focus on anything increases vs. jumping from idea to idea, my legs feel warm with keenly-aware body movement vs walking from Point A to Point B, and I have an overall calmer attitude. It's more than being super-engaged something interesting. It also feels much better while and after.