Used to walk a lot more, but sadly old age is catching up with our dog and he can't cope with the 15-20 mile walks we used to do together on weekends and holidays any more. A few years ago we'd go up to Northumberland for a week and walk that distance every day, and we'd be up in the Washburn Valley, Calder Valley or Yorkshire Dales most weekends, but he's only able to cope with 10 minutes or so a couple of times a day now.
So cycling is my main exercise.
I still try and get in a walk of at least a mile at lunchtime (or more if I have time), as much to get out of the office as anything - plus I'm at an age where I need to keep things moving!