Paul "boasts" of all that he's suffered in spreading the Gospel. He endured a great number of trials and tribulations in his efforts to make new and mature Christians. He was willing to do hard things because of his great love for Jesus.
God called Jonah to do hard things: Preach to the Ninevites. But Jonah was afraid, so he tried to run away. By God's grace, he was spared from death and given a second chance. He was going to do the hard things that God had called him to do.