Paul Preached Boring Sermons

Paul preached boring sermons. He was about the only preacher recorded in the Bible that actually bored someone to death.
And a young man named Eutychus, sitting at the window, sank into a deep sleep as Paul talked still longer. And being overcome by sleep, he fell down from the third story and was taken up dead. (Acts 20:9 ESV)

But the power of Paul's letters can still be felt among us today.
For they say, "His letters are weighty and strong, but his bodily presence is weak, and his speech of no account." (2 Corinthians 10:10 ESV)

This is the secret. You will never find any quotable quotes from Paul, but the power of the Holy Spirit is in his words.
And when I came to you, brethren, I did not come with superiority of speech or of wisdom, proclaiming to you the testimony of God. For I determined to know nothing among you except Jesus Christ, and Him crucified. I was with you in weakness and in fear and in much trembling, and my message and my preaching were not in persuasive words of wisdom, but in demonstration of the Spirit and of power, so that your faith would not rest on the wisdom of men, but on the power of God. (1 Corinthians 2:1-5 NASB)

So if we listen to inspiring preachers, we must examine ourselves to see if we are moved by the preacher or by the Holy Spirit.