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.
Sex is very different to the activities he listed. His activities are all about feelings of calm focus, flow, almost meditative joy. You feel pleasantly recharged at the end of it.
Sex is usually very different and all about dopamine-like immediate intense pleasure, excitement, adrenaline. You can build dopamine tolerance and start needing more for the same 'kick'. Afterwards you can end up feeling more low than before due to a dopamine 'valley'. Then there is also the 'Coolidge effect'.
I suspect very different neurotransmitters are involved.
In other words, to exaggerate: the feeling of being in the zone you get from 'repairing stuff' is as similar to the feeling from sex, as the enjoyment of practicing calligraphy or meditation or tai chi is similar to taking heroin.
