I spend a lot of time measuring things. I measure my work in steel to .0001" or better. I get a consistent body weight every morning at a certain time to .1 of a pound. I want to know how hard I can climb on rock to the letter grade or how fast I run a 5 K to the second.
I want to know if I am in the black on a target. Is it in the X ring or just a 10. I want to know how many pull ups and sit ups I can do and my blood pressure and resting HR every morning. My Max HR on the bike and on a run. And I want to know what my dbl boots and my bikes weigh to the gram.
I measure because I want to do better. If you aren't measuring how do you know if you are doing better? The fact is you don't. The flip side of that is if you aren't getting better you are getting worse. If you don't measure you don't know what is better or what is worse. There is nothing that takes any kind of physical skill that stays the same for long. Use it or loose it. Measuring it will help you keep it or better yet get better at it.