There’s a great book by Arthur Brooks called From Strength to Strength which has a slightly different take on “reality minus expectations”: think of it as a fraction, where what you have is the numerator and what you want is the denominator. If you keep ratcheting up what you want (which is what the hedonic treadmill is all about —- you reach a goal and enjoy it for a nanosecond and then suddenly you need an even bigger achievement to satisfy you), you push happiness further away. And conversely, if you learn to want things that are actually in reach, you become happier as you achieve them.