One reason missions numbers may be down is that it’s usually non-missionaries that are urging young people to become missionaries. Missionaries are the best pleaders for missions.
The old Greek philosophers used to say that three items made a persuasive speech. First, you need logos. You need the right word, content and doctrine. Second, you need pathos. You need the right passion, feeling and emotion. Third, you need ethos. You need the proper character behind the speech. They viewed the ethos of the speaker as the most persuasive part of the speech.