Most of 1 Corinthians has been talking about things the people in Corinth are doing wrong. Here Paul is talking about a belief that there is no resurrection of the dead. He points out that Jesus was resurrected, the resurrection was witnessed by many and is the basis for the Christian faith. He tells them they will be resurrected with new bodies for eternal life.
Day after day we focus on this life. How are we going to provide for ourselves? How do we get people to like us? How can we make our bodies look or work better? This present life is like a seed that will be planted when we die to become something greater. This life matters, but the one to come matters much more. Which gets your greater attention?