I used to often struggle with #12 as the need to measure and quantify all things was rooted in a lot of my activities. As a past, or occasional runner now, I often was meticulous about tracking data and hitting targets. Currently, with Brazilian Jiu Jitsu (BJJ), this method of tracking is almost impossible and I have to constantly face myself and progress is measured in sparring results not an apple watch. So, I totally agree with you that pushing yourself and achieving a personal best without anyone needing to know is powerful and definitely an important mental exercise.