We are never so happy or so unhappy as we suppose.

Both the expectation and the memory run hotter than the experience. You imagine the promotion or the holiday will be transforming, and it is pleasant for a week; you dread the loss and it is bad, though not with the totality you pictured, because ordinary life keeps interrupting with meals and weather and small requirements. The extremes exist mostly in anticipation and in recollection.

When you catch yourself certain that something will be unbearable or perfect, write down what you actually expect to feel. Look at the note afterwards, and let the pattern make you a little calmer about the next one.