If you can enjoy the game even when you are losing then you have the right mindset and you can start playing. Otherwise you shouldn't even start.
How can anyone enjoy losing?
NBA Players when they lose a game they are not too worried because they still get a fat paycheck, but a gambler who's losing surely won't enjoy it?
This assertion contradicts the reactions of other players and mine personally to losing a game. I can see pretty often in the chat of a poker table someone posting "gg" after losing all-in which means "good game", and I think people mean it when they say it, because I do.
Regarding the NBA players, I don't think they are not too worried after losing a game, because they know well this could be the beginning of the end of their career. I think that they are actually much more worried in this case than a gambler after losing five bucks in a poker tournament.