I'll Bite My Tongue, I Won't Say Anything. It's Her Decision

I feel that way about my sister because she's a heavy smoker. So I have to bite my tongue and not tell her to cut down on her smoking or reduce the amount she's smoking. Another expression you could use, which has a very similar meaning, is to hold your tongue,. You are keeping your tongue in your mouth and making the decision not to speak. Don't say anything. Just bite your tongue.