Trenzalore.
He promises himself he will remember this name. He'll hold onto it, he'll keep it deep inside and then---and then---well, he'll just have to do something about it, won't he?
Always facing down the fear of death. The Doctor had been convinced that this death, the one he was running from with his romance with Elizabeth, would be his last. He won't remember that he's going to regenerate, that he's not going to end. He'll go back to running. He'll always be running.
He looks at the scanner outside, of his future self and Clara, just waiting for him to go. He doesn't want to go. He doesn't want to think about the knocking, about how he's so convinced of his own death that he can't stop running.
He pulls the parking brake. I don't want to go.
Memories start to fade, even as the TARDIS starts him on his journey, starts him moving, backwards in time. Somewhere he needs to go. Somewhere he should go.