The ability to say I don't know

 Many smart people know a lot of facts, but they are very unhappy.

I know people who are half as knowledgeable and live fantastic life.

It's all about the focus. A long time ago I heard the following phrase. Would you like to be happy or would you like to be right?

You might think that all the knowledge gives you happiness and the fact that you can state it to others how much you know. But sadly, this costs you your happiness.

I am still fascinated about the people who watch all those game shows, but I know better that having the right knowledge focused on the right activities is way more valuable than having encyclopedia knowledge.

So sometimes, by saying no and focusing on your own things is way more valuable than wasting your time by watching and reading so many facts.