What do you focus on poker?

Poker games are very popular all over the world, I wonder know when people play poker, what do they focus on? Math? Human behavior? Poker strategy? Poker theory? Analyze session errors? Cash games strategy? Videos of live/online tournaments?

In my opinion, I think that I can learn more from poker, but I don’t know what people should focus more at poker games. But like math, human behavior, or poker strategy, we usually can focus on in poker games, and have no one focus more. When we are playing poker, we will use mathematics to calculate the odds, and now and then observe the expression and behavior of other poker players, from the carefully observation, we can get more information. Otherwise, when we lose too many times, we often analyze the session errors, and know what have happened and find the reasons for our losing. In addition, we will learn poker theory from books to increase the poker strategy. Certainly, when we play poker, we hope that we can acquire something, relax ourselves or win money and so on.