In The Night of the Doctor, the Doctor is resurrected by the Sisterhood of Karn before being told that he has little more than four minutes left until he regenerates. The Doctor, even facing his current incarnation's death, states that four minutes is an eternity, then rattles off a list of things he could do in that time. Granted, to one that can come and go in time as he pleases, any duration of time could last as little or as long as he wanted, but in real world terms, he was making the best with what short time he had remaining, looking to live each minute to its fullest, with no regrets. The whole "time is what you make of it" mentality wasn't solely the Eighth Doctor's way of thinking. The Tenth also made a statement in The Lazarus Experiment that someone who was only 20 years old could have lived a fuller life than someone who was aged 80. Lesson Learned: Live each moment as if it could be your last. Even with a short amount of time, a lot can be accomplished.