Expect Disappointment

Demanding perfection is a good way to generate unhappiness.

A slightly forlorn-looking blue one, with a nub with a porthole.

One great source of unhappiness is un-met expectations. If you demand perfection, then your expectations will never be met, since perfection is impossible. Or even if it is possible, it will not last.

With a Buddhist slant, we might say that desire/attachment is the root of unhappiness, but I think these are all essentially the same thing. When you desire something, on some level it is already yours in your mind. And since it is yours, you expect to keep it. When it becomes clear that it is not yours, that expectation is broken, your desire is thwarted, and you are unhappy.

Looks like a truck ran over it, messily. Green.
Looks like a truck ran over it, messily. Green. The other side, showing a leathery texture and chocolate exposed.

They say there are no poor people in America — only temporarily embarrassed millionaires. We all expect to return to our natural state of riches Some Day Soon™.

An orange crescent moon, with some unevenly-coated bits in the concave part.

But we were never rich, and may never be. Even most rich people are not rich, to be sure. The trick is to try to find some value in your life outside of the notion the world owes you something (because it doesn't).

Orange double nut, with a sizeable uncoated patch and a crack, sprawling on the floor.
A blue nut mess. Sunken sides, grainy bits, mottled.
A nearly normal red plain one, but with a lump compressing the right side of its 'm'