Adventists have activities for young people called the "pathfinders programme". It's a bit like the scouts or guides. They teach young people basic skills, get them to work in groups as young people, and with adults, and they learn personal, social and spiritual skills along the way.
Christadelphians have a programme called the "isolation league". It sounds pretty sinister first! But actually it's an attempt to make sure no one in their community feels alone or isolated. So younger ones reach out by making visits, phoning or writing letters and emails.
But as long as JW elders make sure they read the Bible clearly at the meetings that's the main thing.