I learned about it first when I was undertaking Sarah Wilson's I Quit Sugar program. The concept was introduced to help combat sugar cravings when we started to miss our 'sugar hits' by filling our diets with so much other food and snacks that we literally didn't have room for the sugar, hence the 'crowding out' effect.
For example maybe you are saving up for a big ticket item. If you were to focus on all the things you can't do for this period, like dining out or having big nights on the town, you might get down about it and feel as if your goal is unsustainable. If you focus instead on all of the things you CAN do, it makes the task much easier.
Brainstorm everything you are allowed to do within your current goals and restrictions. Get creative, this is what the internet is for!
If you are trying to eat healthy then look up recipes on all of the fantastic blogs out there and start compiling them so you can list out all of the things you can (and are) looking forward to eating on this new plan. Or if your money is going into a new business investment, look at some ways you can enjoy yourself and invest things other than money into your personal life and relationships.
The idea is to look for alternative ways to fill the voids. If you plan ahead and pack in your day with lots of alternative options you won't even give your brain the room to ponder what it is missing out on. Get busy having so much fun that before you know it, you'll be reaching your goal!
After you have finished brainstorming (and probably spent way too long scrolling through blogs) it's time to implement that list. Get out some kind of calendar or planner and start filling it in. If it's a food goal, use a meal planner and include what prep you need to do the night before or in the morning before work.
Identify possible 'threats' to your master plan. What are your weaknesses? What social situations or invitations are going to come along and try to sabotage your efforts? Pin point those and have a plan on how you are going to deal with them.
What do you think- have you successfully used this technique before? What else could it be applied to?