The first will be last and the last first???

31But many who are first will be last, and the last first." Mark 10:31(NIV)

I have never quite understood this verse. I am still not sure this is what it means, but here is what I have come to the conclusion on...as of right now: If you read it as: Those who put themselves first will be the last to enter the gates of heaven, but those who but others ahead of themselves, they will be the first to enter the gates of heaven. The idea that we are not here to be served by this world, but rather to serve others...to help out your neighbor, the homeless, the less fortunate...to try to make this world a better place, even if that means personal self sacrifice. We often get caught up in the mindset that the world owes me, I need to look out for number one, do whatever need be to get ahead. The Lord wants us to love one another, help each other out, and try to leave this world a little better than the way we found it....even if it means sacrificing our own personal interests. That is what I think Jesus was trying to get across with this versus.