Jesus exposed his heart
When Lazarus died, Jesus wept in front of his disciples. God cried.
His disciples got to see the depth of sincerity that Jesus felt toward the people they were ministering to. This mission is not just a job to pay the bills, or some sort of pointless adventure—Jesus meant it. The wages of sin are right before us, and it's worth God crying over.
We should show emotion too. If we don't have emotion we should pray for a softened heart, because every day in ministry the effects of sin are laid bare. The practical implications of sin are so atrocious, and the goodness of our holy and just savior is so real, that we ought to have overflowing emotion at times. Our disciples must see this, they must know that it's real beyond the point of head knowledge, and that it's real even in the deepest depths of our hearts.
Jesus was cautious in his interactions with his disciples
Jesus showed emotion in front of his disciples, but he didn't entrust himself to them because he knew what was in their hearts. In other words, he didn't put his trust in his disciples because he understood the implications of total depravity. His disciples were sinners, and they would disappoint. Jesus was clear that he was absolutely dependent on the Father, and his disciples would need to be as well.
The goal of discipleship is not to put faith in the next generation; the goal is to put faith in God's unfolding and sovereign plan.
This is a series of reflections on how Jesus made disciples, based on the book of John.