Lǎoshī shuō de měi yí jù huà, tā dōu fàng zài xīnshàng.
He takes every word his teacher says to heart.
Tips
usage
Most often negative: 别放在心上, "never mind, don't let it bother you", is a common reply to an apology, and 没放在心上 means "didn't give it a thought". With 把 it names what one cares about: 把客户的需要放在心上, "to keep customers' needs in mind".