(In Mark's Gospel, which was written earlier than Matthew, it is the two sons who directly ask Jesus for special places in the kingdom. Matthew, however, seems to want to spare James and John so he has their mother put the question to Jesus.)
The problem here is that James and John (and their mother!) are thinking of the glory of the kingdom rather than the struggles in this world that help to bring about the kingdom of God. True honor in the kingdom comes from accepting the "cup" - the sufferings involved in working to bring it about.
Earlier in Matthew's Gospel, Jesus uses an interesting metaphor to describe our role in helping to bring about God's great enterprise: "The kingdom of heaven is like yeast that a woman took and mixed with three measures of wheat flour until the whole batch was leavened." (Matthew 13:34)
On a given day, do you affect the world around you even in small ways, like a bit of leaven affect the dough?
Or do you have no effect at all?
- Little Black Book, Diocese of Saginaw