Don't kick against the goads?

In Paul's testimony before King Agrippa, he recounted the trip to Damascus when the Lord spoke to him:
"We all fell to the ground, and I heard a voice saying to me in Aramaic, ‘Saul, Saul, why do you persecute me? It is hard for you to kick against the goads.’" (Acts 26:14)

What does "kicking against the goads" mean?

I really like this explanation from wiki.answers.com:
Interesting question. There is some discrepancy about that verse, because "kick against the goads" is actually not in the original manuscript of Acts 9:5 that tells the story of Paul's conversion. Some think that an overzealous monk may have added it when transcribing when it appears later in Paul's retelling of the event in Acts 26:14. But more than likely, it was either 1) something that Paul received personally from God during the event or 2) a then common day proverb that, in hindsight, Paul later related his pre-conversion life to.

Ultimately, "kick against the goads" is a metaphor. Goads were used to prod cattle and livestock forward, and they would frequently kick back at them, only causing themselves more injury. The thought is that Paul has been kicking against God's "goading," and God has been trying to urge him to go in a certain direction.

The relation in modern day is that Paul is telling us that people still "kick against the goads" today. There is a way of right life & right belief but we fight it. And in doing so, we aren't hurting God... we are only hurting ourselves.

Michael Houdmann, CEO of gotquestions.org gave this application:
There is a powerful lesson in the ancient Greek proverb. We, too, find it hard to kick against the goads. Solomon wrote, “Stern discipline awaits him who leaves the path” (Proverbs 15:10). When we choose to disobey God, we become like the rebellious ox—driving the goad deeper and deeper. “The way of the unfaithful is hard” (Proverbs 13:15). How much better to heed God’s voice, to listen to the pangs of conscience! By resisting God’s authority we are only punishing ourselves.

C.H. Spurgeon delivered this sermon #709 he named "Kicking Against the Pricks". I'll take some of the points he made as my take home message:

1. Don't be an ox! Don't be like this dumb beast, which despite God's gentle prodding, has a propensity to wander away; or worse, to push back at God only to suffer the consequences of my own folly.
2. Listen to the goads! His discipline can be sharp and uncomfortable. But it's for my good. As long as I follow its guidance I won't be hurt.
3. And don't kick (against the goads)! Don't rebel against the teachings of the Bible. Don't sneer against those who kindly advise us. Don't "persecute" God's people (maybe not as bad as Paul, but do I ignore or mistreat those who belong to the household of God?).

"Do not turn to the right or the left; keep your foot from evil." (Proverbs 4)