Your emotions are meant to fluctuate, just like your blood pressure is meant to fluctuate. It's a system that's supposed to move back and forth, between happy and unhappy. That's how the system guides you through the world.
The secret of happiness is variety, but the secret of variety, like the secret of all spices, is knowing when to use it.
I think good things are happening to me and will continue. I am not optimistic about the rest of the species, but I'm so blessed, it's almost scary. I'm sorry to disappoint you, but I have a wildly sunny disposition. I love to laugh.
The mistakes we make when we try to imagine our personal futures are also lawful, regular, and systematic. They, too, have a pattern that tells us about the powers and limits of foresight in much the same way that optical illusions tell us about the powers and limits of eyesight.
Part of us believes the new car is better because it lasts longer. But, in fact, that's the worst thing about the new car. It will stay around to disappoint you, whereas a trip to Europe is over. It evaporates. It has the good sense to go away, and you are left with nothing but a wonderful memory.
No one likes to be criticized, of course, but if the things we successfully strive for do not make our future selves happy, or if the things we unsuccessfully avoid do, then it seems reasonable (if somewhat ungracious) for them to cast a disparaging glance backward and wonder what the hell we were thinking.
If I wanted to know what a certain future would feel like to me, I would find someone who is already living that future. If I wonder what it's like to become a lawyer or marry a busy executive or eat at a particular restaurant, my best bet is to find people who have actually done these things and see how happy they are.