Author here. Previous time this was on the front page: https://news.ycombinator.com/item?id=30930985
As an update, I temporarily relocated to a different city and spent four months training Judo for five hours every day and have since reached the vocab point for the sport. That experiment was covered here: https://commoncog.com/expertise-acceleration-experiment-judo... and https://commoncog.com/mental-strength-judo-life/