How happy would I be with what I don't have

You may have a list of things to achieve in life: having a house, owning a German car—perhaps a Tesla—, or having a family. You tend to think about how happy you would be if you had those things—if you haven't them right now.

But instead of thinking about the future, reflect on the past. For example, think about something that took a great effort and time to achieve, and after accomplished, it didn't change the game. The contentment on achieving something lasts for a few days, weeks, or maybe a couple of years, but it eventually fades.

Most of the things that you have right now were past desires or goals that you finally achieved. Today you don't think about those things anymore, because you got used to them quickly. The achievements have a tenure like the engineers at Google.

Indeed, I always think about how happy would I be if I worked at Google, how my family and colleagues would respect me, and how nice it would be to have that line written on my CV. Then I consider the ~2 years average tenure at the big G. How engineers who achieved the dream, making six figures a year, quit Google after a couple of years. They want it, they get it, they have it, they don't want it anymore.

The conclusion is that things or certain circumstances will never make you happy. Not having that thing is false a promise of happiness, that after its resolution, it goes out of the list, and another not-having-thing appears at the end of it.