No one can obtain felicity by pursuit. This explains why one of the elements of being happy is the feeling that a debt of gratitude is owed, a debt impossible to pay. Now, we do not owe gratitude to ourselves. To be conscious of gratitude is to acknowledge a gift.
Josef Pieper... each gratification points to the ultimate one, and that all happiness has some connection with eternal beatitude. Some connection, if only this: that every fulfillment this side of Heaven instantly reveals its inadequacy. It is immediately evident that such satisfactions are not enough; they are not what we have really sought; they cannot really satisfy us at all.
Josef Pieper