Be stupid! Seriously.
It's not that stupid people have more fun or that they are more creative, and eventually more successful. Don't worry - they don't even get laid more often than smart people (I really hope so). And don't blame Diesel for their campaign, it's all about marketing, and in the end of the day it's all about money.
The only reason why you, and actually all of us, need to be stupid, is because stupid people are simply happier. The smarter you are, the more miserable you become. Fact.
Genius artists, remarkable writers, historical leaders, scientists, fashion designers, musicians - all of them ended up the same way. And you know what - if you cannot recognize the faces below - go out, drink champagne, and then sleep like a log, because, my dear, you've been already halfway to happiness.
I don't say that stupid people might not put a bullet in their head neither. Yes, of course it can happen, but the reason there is most probably the pure absence of any senses or whatsoever rather than a fatal exhaustion to cope emotionally with the exigencies of life.
"Happiness in intelligent people is the rarest thing I have ever seen". And this comes from Ernest Hemingway...who took his own life in 1961.