Rubyiris- It's hard. When you feel yourself getting angry you have to stop, hold it in and talk yourself out of it. You have to do it enough until you're programmed to feel a certain way after something bad or good happens.
I'm still working on it myself.
Ok, I read your whole first post, and I also noticed M2k playing the same way as Mango, or, I mean, laughing as he played. (I mean at a small local, at Rom3 I'm sure he would need to have had a more serious attitude to win that LOL)
Thing is, I don't think I could LAUGH things off... because, I'm trying my hardest, and playing seriously.
Of course, when I'm dying, I'll usually go like "NOOOOOOOOOOOOOOOOOOOO" but not like "ARRGHH NOOOOO I HATE THIS GAEM".
So I'm not LAUGHING when I'm getting combo'd... I'm TRYING my best to get out of it.
I mean, laughing would make you more relaxed, correct?
Now I go ARGHHHHHH NO when I get a phantom fsmash and die, but of course, I'm not screaming in an angry manner, just being LOUD. lol... But maybe I shouldn't go Argh no after seeing a phantom fsmash, lol.

That, should be no problem for me, I believe in the heart of the cards.
And I'm doc, my recovery sucks, but I TRY VERY HARD to come back.
and I WILL ALWAYS say that I will make a come back.
If I'm at 1 stock, I try my hardest to get 2 stock. (3 is very hard though, LOL I haven't ever done that)
AND YES. I do tell people to believe in the heart of the cards, or to just BELIEVE. : ]
Or I support them, and I say "YOU CAN BRING THIS BACK!" even if they are fighting M2k.
If my friend is fighting Eggm, and is still near a beginning level, I'll say "You can beat him, he's a noob" but Eggm knows I'm only joking, and I know that he is very good.