極端 きょくたん はし
kyokutanni hashiru

Godan Verb (ru)
Expression

1. to go to extremes; to go to excess; to go too far

何事 なにごとでも極端 きょくたん はしるのはよくない。
nanigotodemo kyokutanni hashiru nowa yokunai.
You must not go to extremes in anything.