From one point of view this gospel passage has an almost comical aspect if we view it through the modern stereotype of the Jewish mother.  Her James and John don't seem to object to her ambitions for her boys.... 

But who are the sons?  There is more humor when we read (in Mark 3:14-19) that Jesus nicknamed them “the Sons of Thunder.”  Why would He do such a thing? 

Well, in Mark 9:38-40 we read "Teacher," said John, "we saw a man driving out demons in your name and we told him to stop, because he was not one of us."  That's a rather bold assumption of authority. 

And Luke 9:51-56 has “[a certain Samaritan village] did not receive Him because He was traveling toward Jerusalem.  When His disciples James and John saw this, they said 'Lord, do You want us to command fire to come down from heaven and consume them?'  But He turned and rebuked them, and they went on to another village.”

Both of these synoptic gospels seem to present the brothers as rather energetic and zealous young men whom Jesus loved but found at least some reason to tease --- and they turned into two of the most important saints of the post-Pentecost Church. 

The question then is, as always, what does that say to us?  Are we willing to be bold and zealous and allow ourselves to dare to make mistakes in the Lord's service and praise?  Are we ready to be rebuked and, as well, encouraged to learn from those mistakes and try again?