One thing I am learning from my husband is the importance of speaking the truth, even where you are tempted to think it doesn't matter or won't make any impact.
Hebrews says not to be "sluggish" (6:12), and there are different ways to be sluggish besides being a couch potato, one of them being speech sluggishness. This has been my way.
But what my husband has drummed into me is that speaking the truth to a person or into a situation, even if it does not seem that the person is particularly interested or disposed, is putting out a testimony that God can work with in that person's life.
There are certain things that the Holy Spirit "works" with: He does not work with your lies. (He is far away from that scene.) He does not work with your whining. (The devil is the one making hay of that.) But whenever you aspirate a word of truth-a word in line with God's mind and will and character-it is an unretractable insertion into that person's soul. It will perform that for which God has sent it.
It might not be today, it might not be tomorrow. But it is in there! It is part of that person's makeup now, as surely as all the other words that the person has taken in over the years, for good or for ill-all the foolish words, all the hurtful words, all the lousy lyrics of abominable songs.
But the difference is that lousy words and lies are but "for a moment" (Proverbs 12:19) whereas the words that are aligned with God's truth are different in quality from every other kind of utterance, having power to effect transformations:
"… The words I have spoken to you are spirit and life" (John 6:63).
When we bother to speak the truth to someone, rather than keeping our mouths shut out of either lack of caring or out of a deficient apprehension of the power of God's words, we create an entry point for the Spirit to work in that person's life hereafter.
And so the other day when my daughter handed me a natural opening to speak a word of the gospel, I did something unusual for me and spoke it. She made no response at all. But the words had made a difference in her. I could tell.