More on expectations...

Another trick about the human mind is that it takes about 3 months before the current reality of a person becomes his "normal" reality. Say a person wins the lottery, he will initially be ecstatic and continue to be less and less happy over 3 months until this new reality of "having a million dollars" becomes his "normal" reality and it doesn't make him happy anymore. In fact, after this, if he losses the million dollars, he becomes much less happy then he was before, because he has come to expect to have the million dollars. 

So when you are about to make a large purchase that will significantly improve your lifestyle, think about whether you can continue to afford this step up in standard of living, especially if it comes with a corresponding increase in cost of living. Some examples are getting a car when you never had one, getting a maid, moving to live in a condominium from a HDB etc. The happiness you will experience will at most last 3 months, but if in the future you have to give up this luxury and go back to how your life was before, the disappointment might not be worth the original upgrade in the first place.  

One way to apply this practically is when you receive a raise in your income or have a new income source. Understand that spending that new money might only lead to temporary happiness, while not spending it will lead to long term financial stability and freedom. More details on this savings tip here.