opportunity cost

I will never forget the time when a very successful friend of mine told me he could not afford to see a movie. At the time, he was making more than $.5M a year so I questioned him about this. He explained to a very young Ron Browning that it was not the cost of the movie, but the cost of him not spending the same amount of time working on his business. Since he was earning an average of $200/hr it would cost him $400 to see the movie. While I admit this is a bit extreme it gave me a better perspective on the way I spent my time.