Well, in this instance, the Doctor watched me die. He can't go back into our own timeline and change it because it changes everything he did after that. Paradox. So because of that, my death has to happen the way that it does. The Time Lords had technology that could a person between their last heartbeat and death. He was sneaky and got them to use it on me. It also means I can't die in any other way than that, and I'm not going to age.
Lesson plans. Read one of the millions of books we have in the TARDIS. Watch telly. Grade papers. Go for a walk. Swim in the TARDIS pool. Try on clothes from various eras. Travel around and check out Paris while everyone in Texas is asleep. Things like that.