For some of us, it's the feeling of methodically and meticulously cleaning tack. For others, it's the repetition of braiding a mane. For others, it's the quiet moments of filling the water buckets or sweeping the barn aisle after everyone has left for the night.
I love this particular topic, and actually I was thinking about posting about it this week anyway!
For me, it has to be sweeping the barn aisle. The first barn I ever worked at was ob.sess.ive. in its attention to detail in that way, and I would sweep 3-4 times while doing chores to make sure I cleaned as I went. I found a rhythm and a happiness in the way I worked. There was a particularly awesome Lab mix dog at that barn, too, who would chase the little bits of hay if I swept particularly vigorously. We made it our little game.
Even now, there is something absolutely hypnotic about a good broom and a long barn aisle. Getting the turn just right, getting the finish flick just right, overlapping your strokes in just the right way. I love it.