我的体能真的退步了。

Wǒde tǐnéng zhēn de tuìbù le.

My fitness really has declined.

你再不努力就会退步。

Nǐ zài bù nǔlì jiù huì tuìbù.

If you don’t work harder, you’ll fall behind.

这次考试我退步了，成绩比上次差。

Zhè cì kǎoshì wǒ tuìbùle, chéngjì bǐ shàngcì chà.

I regressed in this exam, my grades are worse than last time.