Ask HN: How to measure personal growth?

HN, how are you measuring your own personal growth? How do you KNOW you're better today at X, than you were a year ago? What metrics do you track? What system do you have in place to do the tracking?

This question was inspired by Jessica Livingston's "How Not to Fail" speech (http://themacro.com/articles/2016/06/how-not-to-fail/), point #4.