I've got a pedometer app on my phone which I was going to suggest ... but then I remembered that you don't have a smart phone Grendel!
In all seriousness while it can become obsessive to carry my phone around all day to get my steps counted, the monthly target it sets you is a good motivation.
This month I needed to walk 60 miles. I've got 2 miles left to do so should just about achieve it. I know that exercise isn't going to fix my poor diet, but I know that I can walk further than I used to since I started using this. And I am getting out most days where it would have been so easy not to bother given that I'm working full time still.