Simulating the future
Your future might be someone else's present. Use that as a reasonable prediction
You might think that you can predict how you would feel in the case of a future promotion or a move between countries. As Daniel Gilbert draws on research in his book, Stumbling on Happiness, you cannot:
Put in perspective all the other life stuff1;
Consider how hunger, anger or tiredness will affect you; and
Anticipate how the brain fills in the gaps for the past, but not for the future.
But then what should you do? Ask people who are currently in the same situation how they feel now. And then believe it.
Memories won’t work due to the same reasons. You can use this to plan your career. Ask people who are just ahead of you what you need to make a move forward. More senior people might have much more wisdom, though some of it might not be applicable, especially in fast-changing fields.
And the most self-promoting closing I will ever pull off: this is what I am doing here, recording my feelings and thoughts on the spot, hoping that it will be a reasonable account of what happened and how I felt then.
That is, you will still need to bring out the trash