1 Corinthians 15

Though Paul's purpose was to explain and testify concerning the resurrection, I noted his feelings as he commented -

"And last of all he was seen of me also, as of one born out of due time.
9 For I am the least of the apostles, that am not meet 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 which was bestowed upon me was not in vain; but I laboured more abundantly than they all: yet not I, but the grace of God which was with me."  (New Testament | 1 Corinthians 15:8 - 10)

In my mind,  Paul is suggesting that he recognized, in being an apostle, was one that once persecuted the Church.  And because of that did not feel the same worthiness or greatness of those apostles the Savior called himself.  But what Paul did say that I felt is important that even though he may have felt somewhat less than, he acknowledge how he was greatly blessed by the grace of God to fulfill his office even acknowledging that he had a greater obligation because of that grace to maybe work harder and sacrifice more than previous apostles.

I sometimes feel because of my past, my weaknesses, imperfections, and inadequacies, that I have a greater obligation to work and sacrifice more than maybe others in my calling.