For fellow geeks and people who like records of stuff - I love the WalkJogRun app (I use it on iPhone, no idea if other platforms available). It uses GPS to track your routes on a map, tell you how many miles you walked, your pace, etc. You can also use it to find routes other people have put in, whatever length you're looking for. I know there are several apps that do this but this is the one I use and I love it.
One of my favorite things is to look at the data from the last 30 workouts. For me that covers about 6 weeks, during which time I've walked 74 miles.
You can also use it to manually enter treadmill walks or runs and other types of workouts.
I find geeky little things like this highly motivating!