A novel theory of time discounting is proposed in which future consumption is less valuable than present consumption due to waiting costs. Waiting is intermittent as consumer's attention can be distracted away from future gratifications. The model unifies several properties of intertemporal preference like present bias, decreasing impatience or sub-additive discounting. A quantitative puzzle is presented, supported by preliminary experimental evidence, which shows how impatience over short delays may translate into excessive impatience over long delays. The wait-based model offers a solution to the puzzle, contrary to usual models of discounting. J.E.L. codes: D8, E21