Every time I see this, I ask myself, how is this advice reconciled with the famous Marshmallow experiment? http://en.wikipedia.org/wiki/Stanford_marshmallow_experiment
There surely must come a point where enough deferred future marshmallow gratification makes deferred gratification a recommended life strategy.
If I were always to choose not to delay my happiness, I'd eat unhealthy foods, not force myself to do exercise and never work hard to achieve anything.
As I heard a comic say, "I decided to live every day as if it were my last. Now I have really bad credit."