How do you store a repetitive action in the GTD system?

I'm a GTD (Getting Things Done) noob, trying to get into it - one thing I can't understand is how repetitive actions are worked into the flow of daily life. Of all the GTD applications/systems I've seen thrown around, none seem to allow you to 'program' actions that should come up at some time interval - walk the dog every day at 5:00 PM for 30:00 minutes, eat lunch every day at 12:00 noon for 45:00 minutes - they all just seem to deal with single-shot, do it and it's done type actions. Does anybody have a link about how the GTD system is supposed to handle this?