Batz kinda captured it.
Sure, we are doing what we like (me, finance and accounting, project management, IT stuff) but there are other people involved. Mucking around in our work, slowing us over-acheivers down, sometimes just being crazy.
No matter who you are, it is hard doing the same thing, all day, every day, without summer vacation, and on someone else's time table.
Especially if you could be home playing with the kiddos and the chickens!