Every hour I spent doing that while at Oxford, I wasn't studying applied econometrics. At the time, I was conflicted about whether I could really afford to take that time away from my studies, but I stuck with it. Had I instead spent that hour each day learning the latest techniques for mastering the problems of autocorrelation in regression analysis, I would have badly misspent my life. I apply the tools of econometrics a few times a year, but I apply my knowledge of the purpose of my life every day. This is the most valuable, useful piece of knowledge that I have ever gained.