Yeah, I think most people track two out three of time, distance, and speed. Then you get a general sense of effort involved knowing the terrain or conditions that were present. Over time, you get better estimating and understanding how the activity impacts your appetite and weight loss, diet, etc.
It really is kind of neat to track your resting heart rate and then watch that go down over time as your conditioning improves too. Kind of a positive reinforcement. You can directly see how your diet impacts it too. I use a Fitbit and my understanding is it's mostly accurate most of the time. There was at least one research study I'm aware of that basically said it's good enough for most laypersons' needs.
It really is kind of neat to track your resting heart rate and then watch that go down over time as your conditioning improves too. Kind of a positive reinforcement. You can directly see how your diet impacts it too. I use a Fitbit and my understanding is it's mostly accurate most of the time. There was at least one research study I'm aware of that basically said it's good enough for most laypersons' needs.