You know, basic bookkeeping.
It has proven interesting and informative to me to maintain a document of some basic numbers on things I do. For example, I make sure to check in whenever I’ve worked on a programming thing. I have a tool running that tracks my time spent between different applications. Hell, I even keep track of how many times I ingest alcohol, caffeine, etc. each month, so I have some actual numbers to aid me in keeping tabs on myself.
A slightly different example is how I record all the different routes I take when I go for walks or a ride on the bike. Of course, I can immediately check back for distance, time, and so on, but I can also overlay all routes to see what paths I take frequently, and which ones I haven’t explored yet.
Other people track what they eat, which can be a fun one as well, if not useful towards a certain dietary goal. Those modern health-aware armbands also do a crazy-good job of keeping tabs on your health. And you can have all the data it collects logged in an accessible format, enabling you to let loose your custom analytics on it.
Data’s cool stuff.