For an example, look at Paul in the book of Philippians. Paul says in chapter 3:12
“Not that I have already attained, or am already perfected; but I press on, that I may lay holdof that for which Christ Jesus has also laid hold of me.”
Now, I know that this is kind of an odd verse to choose to make a reference to humility BUT I think it's very interesting what Paul says here and feel like we can learn a lot from his statement.
Paul is saying here that he knew he wasn't perfect; he knew that he hadn't "arrived" at his full potential - that he wasn't everything he knew he needed to be as a Christian. How amazing is it for him to say something like this? I mean, here's somebody who did SO much for the work of the Lord. We have so many examples of the wonderful work that Paul did and the suffering he did and the preaching he did - but yet, here he is saying that he hadn't "attained" a pride of where he stood spiritually.
As Christians striving to grow stronger, we should never think that we have reached our full potential as a Christian or that we have reached our spiritual plateau. Paul warns us of this in 1 Corinthians when he says, "Let he who thinks he stands take heed lest he fall..." We have to make sure that we keep growing each and every day.
2 Peter 3:18 "But grow in the grace and the knowledge of our Lord..."