Sure, I find sex enjoyable, and surely I can get in the zone, but it's a relatively short time an hour at the very best and most of the time shorter, combined with being physically (and mentally somewhat) exhausting and takes some preparation both before and after, it's not a top contender for enjoyable activities for me.

Sure, it's an intense burst of pleasure, but I'd not want to spend 4-5 hours per day doing it, and time is definitely an important component for me, if I can do something for a long time and enjoy that time, that's like an enjoyment multiplier for me, I want something nice and to be in that nice place as long as I can.