Get the PDF and fill out the happiness form. Through the centuries, the Human psychological condition has barely changed. And yet today, it is under more stress than ever before.
Fortunately, this is an area well studied. Unfortunately, the fact that its study alone hasn't yielded considerable result obviously means that we're missing something. Here's what I think it is.
The Stoics of Ancient Greece and Rome had this little trick called negative visualisation. Essentially, you dream up bad stuff to make your current stuff seem great. Call it what you will, this form of reappraisal has immense benefits.
It isn't hard to do this once. But doing this over and over and over again becomes a huge cognitive feat for those without the predisposition to do so.
Hence, we need constant reminders. I stick a sticky note above my work area so that I see this message constantly. This reminder ain't sexy, and is usually not welcome, but whatever it takes, consistency is king.