When teaching adults or teens and up for that matter, all you can provide is a Biblical truth in proper context at the right time to plant a seed or provide a way go do the right thing. That is it. You then have to give up the reins to God and let the Holy Spirit work from there. You see, there is free will that decides within a person whether to hear you or not or whether to obey and be humble or be selfish and go a different way. You can not push a rope or make a person do what they they decide not to do. They have to decide for themselves. When they decide to obey and serve, it is very sweet. When they don’t it is equally hideous and unnerving. One thing you do have co from over is yourself. We have that same free will and can choose to be an excellent example for whomever we wish to teach something to. People are much more likely to hear you if they are familiar to you already and if they respect you. Then you pray and let it go. That is it. That is all we can do.