At some point everyone must have thought about the genie-in-the-lamp scenario, and decided what, given three wishes (and having restrictions on wishing for more wishes, bringing people back from the dead and making people fall in love) they would wish for.
Would it be a new car/house/tropical island?
an eternal supply of chocolate?
or just oceans of money?
Given the chance to ask for anything, what would you go for?
Well, Jesus said "Whatever you ask in my name, this I will do, that the Father may be glorified in the Son. If you ask me for anything in my name, I will do it."
What are we to do with this? Can it really be true? What about the time I asked God to give me the spiritual gift of being able to fly (true story) and it never happened?
Of course we need to look at this verse in context. The slight problem is that "looking at this verse in context" often becomes a euphemism for "find some evidence to suggest that this particular part of the Bible isn't really true, or at least, it doesn't mean anything like what it seems to."
It can be too easy to strip this promise of all its faith-increasing power by mitigating it with conditions like "as long as you ask for something which is within God's will, with the right motivation, with enough faith and you persevere for at least a week." You don't find that in the verse, but neither is Jesus suggesting that He is a magical genie waiting to fulfil our every desire.
This passage will probably always confound those people whose top three wishes are for combinations of money, success, pleasure, prestige or power. It won't make sense because it seems like an amazing offer that Jesus consistently fails to come through on.
For those people, however, whose greatest desire is for the kingdom of heaven to come on earth, to see people saved, healed and set free, this promise is one of the most encouraging in the whole Bible, and should be one of the biggest motivators to prayer. Because it's true.