Necessity is Laid Upon Me

1 Corinthians 9:16
"For though I preach the gospel, I have nothing to glory of: for necessity is laid upon me; yea, woe is unto me, if I preach not the gospel!"

God does not save us so that we can continue living our lives as if nothing happened. There is a reason behind our salvation, a call that He places on the life of each of His children. It varies from person to person, but it cannot be ignored.
Paul knew his calling was to proclaim the Gospel, no matter what. His satisfaction in life was gained through pursuing this goal. Do you think Paul would have been happy being a blacksmith? I doubt it. God called him to be a missionary, a teacher, a preacher. Paul made it clear that he had learned how to be content no matter what life threw at him. However, this contentment came because he knew life's circumstances could never stop him from pursuing his one goal - proclaiming Christ.
What necessity is laid upon me? When I am old, will there be something in my life that causes me 'woe' because I did not do what God had called me to?