A proverb meaning that helpful advice or medicine may be hard to accept or unpleasant; literally, 'good medicine tastes bitter.'
上司の指摘は辛かったが、良薬口に苦しで後で役に立った。
My boss's criticism was harsh, but it was like bitter medicine and proved useful later.
ダイエット中に運動を続けるのはつらいが、良薬口に苦しだと思って頑張る。
Continuing exercise during a diet is tough, but I endure it thinking 'good medicine tastes bitter.'
母は時に厳しく叱るが、それも良薬口に苦しという教えだ。
My mother sometimes scolds strictly, but that's the teaching that 'good medicine tastes bitter.'