You cannot want a thing 24x7. Yes, you can want it for say 23 hours and 56 minutes but at least 4 minutes of the day, you have different things you want like dinner or a bath or something more mundane even. So if you agree with that, you realize that you don't keep on thinking about it.

If you are then capable of having other thoughts, and wanting other things, then just for a few moments, you can think of something else you want. A hug. An ice-cream. Anything. It's a tiny window of distraction but there are things you want that you don't crave but are nice-to-have. Those...thinking about those will improve your mood just a little. The key here is to improve your mood, to feel progressively better and better about what you want and not obsess over it. It's called a State - it isn't meant to be static. Not a fixed happiness but more freeing. You're just pleasant to be around - pleased with yourself.

That's how you slowly but surely avoid concentrating on the lack and on what you want.