You devote two hours a week to sports fandom, you say? How much would you have to be paid to give those two hours up? You’ll be paid in terms of extra time. So if you give up your two hours of sports fandom, the benevolent genie gives you three hours for something else, whatever is your next best activity or activities. That means a net gain of an hour a week and a time rate of return of 50 percent. You won’t do that? How about four hours back and a time rate of return of 100 percent? Nope. Really?
Sports must be fun. Well…why aren’t you watching more sports?
OK, go draw your marginal utility curves and show your MU for sports first way above your MRS and then dropping off a cliff. What’s the hard-to-substitute-for "Lancastrian Z good" that makes sports so imperative for two hours but so inessential for three?