I do some time tracking every day. The latest version, v5, is here.
Believe it or not, it's not actually a lot of work. Periodically through the day, I mark down what tasks I've been working on. At the end of the day, it takes me around 5-10 minutes to tally up how I spent my time (along with some other things - what I ate, how much I spent, appointments I had, general habits I completed or didn't). Again though - this looks like a lot of work, but it's not. It takes work to set up and habituate, but then it's pretty automatic.
Over time, I've broken down how I spend time into four general categories - Excellent, Good, Okay, Bad. "Excellent" includes things like exercising and working on big expansive things. That's really excellent time.
"Good" includes reading and general maintenance-type work that keeps things how things going the way they were. Now, note that "Good" really is good. When I have a day with lots of time in the Good category, I'm happy.