I know someone's who going through a difficult time in his life, and is about to make what he believes is a wise decision, but which I believe wiser minds would say isn't. I'm concerned about him, but what I've come to realize that all of our concern and all of our anxiety over other people should primarily drive us to pray for them. Interventions of course can be a good idea, but they don't always work, and I think they can even deny the ultimate source of all healing and all help that comes to us: God's grace.
Brother Lawrence seemed to have an almost nonchalant attitude towards the salvation of other souls and the redemption of sinners. He told one of his followers that he would pray for them, and then forget about them, trusting in God's power and benevolent mercy to look after the souls of those he prayed for. I know in my own life I was allowed by God to do things that were unwise, and as a result, God brought me back to himself, by transforming the error of my ways.
I will pray for this acquaintance of mine, and forget about it...except to pray again when I think about him. I won't wring my hands in anxiety, and trust him to God's loving and benevolent mercy.