Tristan's very, very favorite thing is doing nothing.
He would summarize doing nothing as eating all alone in a big field. Maybe taking a nap. Maybe walking to a new pile of hay or a new patch of grass from time to time. But mostly foraging without interruption.
He's not a social horse - in fact, he's one of those rare horses that I think would be perfectly happy alone. He's never been a horse to introduce himself to new horses, or hang out with a buddy in the field. He's not a workaholic, and doesn't particularly enjoy work, beyond getting occasionally excited while going XC, or settling into a comfortable sense of mission on a trail ride.
Tristan's idea of the best day ever.