You can share these points with them.
1- Realize whom you have sinned against. Allah has been so kind to you and you still sin against him? You are sinning against the king of the universe. That’s big.
2- Remember the Prophet and the Imams witness your deeds. When you sin you disappoint them.
3- Sins can take away your faith, and one can die an unbeliever God-forbid. They make Shaytan more empowered over us.