I'd just like to note that sometimes people present physicians as an example of people who don't need to work on their field outside of work. These people are horribly informed.

My extended family gatherings are like a medical convention. Both my parents are physicians. Unlike computer science there isn't a question of "do I need to work on medicine to continue to be on the top of my game?" The answer is yes. Period.

As far back as I can remember my parents have always had heated medical discussions on new cases over dinner while my sister and I shared blank stares. When I was 6 or so I remember gathering all the copies of the New England Journal of Medicine, Modern Pathology, and the Journal of Clinical Pathology and using them to make a fort in the apartment. The high ceiling fit me and my sister quite comfortably. My mom spends her time thinking about how things could be done better and more efficiently in her practice and my dad is constantly innovating and forming companies.

So do programmers have to like programming? Do they have to keep up with it outside of their job requirements?

Yes. Period.