Maxwell Maltz said this quote

I have found that one of the commonest causes of unhappiness among my patients is that they are attempting to live their lives on the deferred payment plan. They do not live, or enjoy life now, but wait for some future event or occurrence. They will be happy when they get married, when they get a better job, when they get the house paid for, when they get the children through college, when they have completed some task or won some victory. Invariably, they are disappointed.