I Don't Want To Go
There was a belief across the universe that Time Lords were lucky creatures, for they didn't have to endure death as quickly or as finally as any other species. They lived for thousands of years, and simply rebuilt themselves over and over whenever they became weak or exhausted. In theory, it was the perfect mechanism of cheating death.
The Doctor knew better.
For you see, regeneration was not simply restoring the body to its full health, nor was it saving the body from death. It was completely reinventing oneself so that the person who emerged from the regeneration was entirely new. It was not restoring, it was changing. It was not cheating death, it was being reborn. And the only way to be reborn was to die first. Every time a Time Lord regenerated, they effectively relinquished their life in order to start a new one, with the only remnant from the previous life being a catalogue of memories that haunted and followed them like ghosts of the past.
Time Lords did not rebuild themselves over and over. No. They died over and over, each facet of their being used up and then thrown away and replaced again and again. Incarnation after incarnation killed off in a seemingly endless, merciless cycle of regeneration. The Time Lords were not lucky, they did not live more than any other species, they died more than any other species.
And the Doctor did not want to die again. Not when he had made so many friends and seen so much. He wasn't ready to die and he wasn't ready to be replaced. He wasn't ready to start again. He wanted more time, that's all, more time. But time was the one thing Time Lords were never granted.
As the fire pumped through his veins he knew it was inevitable, he couldn't avoid it now even if he tried, and he had tried many times in this form. He took a deep breath and thought about everything he was going to lose. And the only thing that crossed his mind was "I don't want to go."
And then the Doctor died, for the tenth time.