おやおや。いかな体育の授業といえど・・・真剣勝負の意気込みで臨まなければ、いざ実戦と言う時に役に立ちませんよ。
Oh my. However much it's just a P.E. class; if you don't face it in real earnest, then when it comes to a real fight it won't do you any good.