If the game's too easy for you you get bored, and if it's too hard for you you throw the controller at the wall and hopefully go outside. Someone just graphed it as a function of one thing over the other, which you can theoretically do with just about anything.
Below is a graph of what has been called "fatassedness" by world renowned diet doctor and professor and doctor Mikhailnikov Cznelzignyschkzovkyia, graphed as a function of metabolic rate against how much shit you eat:
According to this graph, it can be seen that eating too much for your metabolic process to handle leads to a rise in body weight, or "fatassedness", while the opposite leads to a corresponding drop in such. Proper amount of food consumption for one's metabolism leads to a perfect wavy red line within a transparent oval, within which you are always hot and sexy. Only choices on the part of the eater can maintain position within the ovoid of sexiness.