because, since, as 理由・原因を表す

I didn't win anything, but I enjoy it.
I didn't win anything in the sushi competition.
何も～ない　何も勝てなかった　何の賞ももらえなかった

I’ｍ really excited. The hiking was really exciting.
I'm really disappointed/excited.　-ed形は｢人｣が主語
私は本当にがっかり/興奮している。
The game was really disappointing/exciting.  -ing形は｢対象物｣が主語
その試合はすごくがっかりだった/興奮した。

Don't be silly. そんな馬鹿な
Don't be sad. そんなになげか（嘆か）ないで
Don't be shy.

Great Nova teachers from around the world come here.
Great sushi chefs from around the world come here. You did your best.

I'm going to....   , but I don't prepare well enough.
I didn't get a prize, because I didn't prepare well enough.

Don't say that, Boris. (相手のネガティブな発言の後に）そんなこと言うなよ～。
You should be proud of it. それは凄いことだよ。（相手に良い事や褒めたい時）
Don't say that, Boris. You should be proud of being here.

That's the spirit. その意気だ！
Thanks, Nikola. I'll learn more techniques and come back again next year.
That's the spirit. You'll definitely get a prize someday!