" research shows that imagining the absence of a positive event in your life has a more powerful effect on you than simply looking back on that positive event. Likewise, imagining the absence of an important person in your life can be more powerful than simply appreciating the fact that they are in your life. One study found that mentally subtracting a material possession you’ve previously enjoyed increases your happiness with that item more than simply thinking back on when you purchased "

― , The Gap and The Gain: The High Achievers' Guide to Happiness, Confidence, and Success