An Unconventional Kingdom (Matthew 20:1-16)

Our Lord teaches,  “the first will be last and the last will be first.”  If this is the case then why would we want to live or work for the Lord if we are just going to be last?  Why would we pursue the Lord if we are not going to receive immediate praise?  Why would our Lord say such a thing in terms of working in his vineyard?  What is our Lord teaching us about the ultimate joy of the Christian life?