After 5 years, I still have to peck at buttons on my watch to pause/unpause workouts or switch songs when I bet you some slap gestures could do the trick
why don't you talk to your watch? That's what I do. I don't find the voice interface that useful on the phone (and completely disabled it on my iPad and Mac -- ugh). But on the watch it makes a lot of sense.
I guess I just don't tweak things much while doing stuff. I only know of one gesture of the kind you mention: cover the watch face with your palm to silence an alarm or incoming call.
