TRACKING things like running mileage, weight, sleep, practice time and whatever else is great, but unless you really visualize that data, it's pretty useless. Datalove, a free app, provides those visualizations so you can really see your progress.
Datalove can manually or automatically track certain kinds of data. Things like running can track automatically, but you can also add in pretty much anything else you want. Once you get a few days worth of data, you can look at charts, track information, and see how you're doing in a visual way. If you love tracking yourself, Datalove is a pretty nice way to actually visualize all that data in a way that makes sense.