The way I read it: The argument starts with the reader being in a gym. So having paid the gym is given and we assume that the gym must provide some sort of valu

The way I read it: The argument starts with the reader being in a gym. So having paid the gym is given and we assume that the gym must provide some sort of value. At some higher fee, the value would be negative and the reader would not have gone to the gym. Rationally. Now the article argues that since the reader would pay more to be in the forest than the gym, they should evaluate their options to run in the forest. Because that could provide more absolute value. Even if it meant travelling further. The only way it makes sense to argue this way is when you're trying to convince a consumer of a non-consumer option that is better. Because, it presumes, only when a consumer evaluates the forest as a product, they will see its value.