sluring words.

I had a conversation with my child about him cutting off the last part of words and talking really fast which no one can understand. i implemented what you suggested of telling him to take a breath but even after he takes a breath he still talks really fast and cuts of the end of the words. Do I just let it go and let it be what it is? I still find myself correcting him every time he talks. I don't want to ruin our relationship. He is 10.