Some people simply will not undertake an activity they wish to improve upon (exercise, coding, playing an instrument etc) without objective numbers guiding them and relaying their progress.

Others, like myself and perhaps OP, are happy enough to undertake an activity and be less scientific about their performance so long as they "feel" they are making progress and more importantly enjoy the activity.

To add to my previous post. I do try to strike a balance. For example the vast majority of the time I don't measure myself, but every now and then for curiosity I'll strap on a heart rate monitor and mobile app like MayMyRun to see how I'm performing versus a few months ago. I still don't have the voice shouting progress in my headphones, and I still run without music, but it's interesting to see the results and a nice outcome if they have improved.

For me, heart rate monitors and Strava have greatly improved my running and cycling enjoyment, as well as made me more likely to run. Strava has lots of metrics, and encourages competition with others, and my heart rate monitor (and accompanying watch that tells me my heart rate) gives me direct feedback to how hard I am running, and if I need to slow down or pick up the pace.