There are several ways that you could measure the distance that you're covering. One way, the most common suggestion, would be to get a pedometer from a local sports store. That might work, but not for everybody, as some aren't 100% accurate. Another way to do it would be to measure the distance with your car. That way is pretty accurate, but there is one other way I know of that could do it, and it's probably the easiest. You could measure it on:
http://www.geodistance.com/
That can measure it probably most simply and more accurately than most pedometers would. To use Geocites, you simply need to zoom in with the scale on the left to where you're trying to measure, or you can use the "Jump to Location" on the top right, and put in the location where you plan to measure. You normally would still need to zoom in more. Once you have found your location, you need to click your starting place, and then click along your route for the red line to follow it and measure your distance. It can also help to change it to to satellite instead of map, as it shows much more things, such as the trees, houses, and such, so that you can be more accurate with your start and finish.
Most of these ways fortunately don't really require you to spend money :).