1 Corinthians 15:8-11

Last of all, as to one untimely born, he appeared also to me. For I am the least of the apostles, unfit to be called an apostle, because I persecuted the church of God. But by the grace of God I am what I am, and his grace toward me has not been 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. Whether then it was I or they, so we proclaim and so you have come to believe.

Paul gives us a little glimpse into his own character here. He calls himself the least of the apostles, those sent to proclaim Christ, yet he says that he works harder than any of them. Do we detect some frustration here? Indeed! There was significant conflict and suspicion between Paul and the first disciples of Jesus. They were pulling in different directions. Paul towards the Gentiles… the others, towards the Jews. But the great insight here is that Paul accepts that “by the grace of God I am what I am.” Such self affirmation was hard won by Paul, the one who had persecuted his fellow apostles. He names this as the grace of God at work. It’s not about his own efforts, its about God working through whomever God chooses.
There is no limit to the things you can accomplish if you are not concerned about who gets the credit.