God had to discipline Jonah for his disobedience. After the sailors tossed Jonah overboard, God sent a huge fish to swallow Jonah. It wouldn't have been pleasant in there. While Jonah sat in that fish's belly, he had a chance to admit his disobedience and choose to do what God wanted him to do.
God gives second chances, and sometimes even third, fourth, and hundredth chances. He doesn't give up on you. When you disobey God, life with him isn't over.
Jonah's story is a good reminder that the lessons you learn from being disciplined will help you become a better person.