I discovered this important truth 3 months after I came back from a back packing trip to Portugal 30 years ago. I had run out of money several days before the return flight home and just got by by drinking warm and ugly tasting water. Finally on the plane, I was given a glass of ice cold sparkling water, which was the best drink I had in my entire life before and after. 3 months later, looking into my fridge full with bottles of sparkling water (literally, and to this day, I have to get up and drive to the gas station to get some, if I run out of sparkling water during the night), I realized that my joy of having cold sparkling water at my disposal was not as intense as 3 months earlier on the plane. I understood then that the way I feel about something depends very much on the perspective from which I look at it. This has helped me become very much an optimist, just as the author of the article says.

I am not sure if you become an optimist by thinking about what could be worse. Rather strive for things to evolve positively as much as you manage to.