1 Corinthians 15:9-11 For I am the least of the apostles, unworthy to be called an apostle, because I persecuted the church of God. 10 But by the grace of God I am what I am, and his grace toward me was not in vain. On the contrary, I worked harder than any of them, though it was not I, but the grace of God that is with me. 11 Whether then it was I or they, so we preach and so you believed.
Did Paul really work harder than the other apostles? If you read the rest of Paul's writings, you get an indication that you can believe that he did. But why would Paul work so hard? Paul's answer is - GRACE. In the above statement to the church at Corinth, Paul made mention of his former unbelieving life. Paul was the least of the apostles because he was very aware of his persecution of the church. He hated the church and every idea of Jesus until the day Jesus confronted him when he was on his way to Damascus. Paul was confronted by grace and experienced the mercy and forgiveness of God through Christ. He went from persecutor to Apostle.
Not only was it not a waste of the grace of God (it was not in vain - it never is), but Paul's experience of grace turned his entire life around. From the moment of his encounter with the risen Christ, Paul became aware that his work as a pharisee was nothing other than his sinful pride of self-righteousness. He became aware that he did not deserve anything from God, but eternal punishment and he became aware that only the work of Christ would save him. Paul went from working for pharisaical entitlement to a life of slavery to Christ in the glory of grace. The prize of Jesus' work for him became more precious to Paul than anything else in the world.
It's not that the other apostles did not understand this, but it does seem that Paul's unique situation promoted a work ethic in his life that resulted in complete sacrifice for the gospel. In multiple places in his letters, he reminds the churches that his mission to them was self-funded. He never expected payment from those to whom he was ministering the gospel. He never wanted there to be anything to suggest that the gospel was for his benefit. 2 Thessalonians 3:7-8 For you yourselves know how you ought to imitate us, because we were not idle when we were with you, 8 nor did we eat anyone's bread without paying for it, but with toil and labor we worked night and day, that we might not be a burden to any of you.
Paul worked harder, but he does not attribute his work to a sense of ascetic piety. He does not suggest his work would get him a better reward or recognition from God or others. Paul says that his working for the gospel was because of the gospel grace that was working in him.
The Christian work ethic should reflect this very grace. Grace doesn't motivate apathy, it motivates action. Grace, active in the life of the church, drives the mission of the church. You should try it... Meditate on God's grace to you in Christ. See if your reflection leads you to affirm apathy or action. I am convinced that anyone who understands the nature of grace, will never come up with an answer of apathy.