One of the overarching messages from the Book of Jonah is compassion. Jonah was a prophet, and even though he had let God down in numerous ways, he was still forgiven because God showed him unlimited love and compassion. God also modeled forgiveness and mercy for Jonah in how God dealt with other people. Compassion is important when you're part of a family or even a community of people with different personality types and life experiences.
God's mercy is extended to all One of the biggest lessons seniors can take from Jonah is that God's mercy is extended to all, despite how followers may feel about this. In fact, in this book, God expresses disappointment in Jonah for believing otherwise.
In chapters three and four of the book, Jonah is upset with God for offering mercy to the people of Nineveh. He gets downright angry because he has forgotten that the God he serves is a forgiving one willing to extend his mercy to all.
The lesson here is that all Christians should want God's mercy for others. It's the reason that you take the time to minister to others because by accepting God into their hearts, they can then receive the mercy they desire.