Steven Moffat has said it is too early for him to feel sad about stepping down from his roles on Doctor Who because "it's hard to be wistful about something that might still kill you".
The writer and executive producer will hand over the job to Broadchurch writer Chris Chibnall at the end of the next series in 2017.
However, he said he cannot yet feel nostalgic about the BBC One show, even though he knows he will be overwhelmed with emotion the day after he gives up the keys to the TARDIS.
He said: "That would be pre-emptively wistful, I don't think you can do pre-emptively nostalgic. I'm sure I will though.
"At the moment, Doctor Who is so utterly full on it feels like a mountain to climb so I can't think of anything other than 'will I survive it'?
"It's hard to be wistful about something that might still kill you but I'm sure the day is coming and I will write a huge angry piece for The Times about how the BBC has lost its way and my phone number and how things were great back in the day. I will do that about the day after I've left."
Steven added he is sure he can wrap up the story he wants to tell before he departs, saying: "Obviously we are Doctor Who and you never want to have finished the story and I'm not going to do that, I'm not going to wrap it all up and say to Chris 'There you go, he's dead', that would be mean.
"The departure of a showrunner and arrival of another doesn't really matter very much."
Steven's last series will see the arrival of new companion Bill Potts, played by Pearl Mackie, following the departure of Jenna Coleman as Clara Oswald.
Peter Capaldi, who will return as the Doctor in Moffat's final series, as well as the upcoming Christmas special, said the departure of Coleman and the arrival of Mackie's character gives the show a new start.
He said: "It was sad and a bit difficult because I was used to her (Coleman) being with me all the time, but Pearl is fantastic and that is a whole different thing.
"Because her character is new to Doctor Who it's almost a kind of reboot, I feel as if the show is sort of more hardcore Doctor Who because it's reduced to its classic elements - which is mysterious stranger from alien planet with time machine takes innocent earth bound companion off to adventures."
The Christmas special, The Return of Doctor Mysterio, will see the Doctor reunited with Matt Lucas's Nardole for a classic superhero story.
The duo will be joined by newcomers Charity Wakefield and Justin Chatwin for the special episode, which Peter is looking forward to watching on Christmas Day.
He said: "I always watched the Christmas special before I was involved and I still do, I watch it from behind the sofa because of my acting.
"I'm so terrified of my acting and my hair but it is still a centrepiece of my day, I wouldn't like to deprive the family of that."
Doctor Who: The Return Of Doctor Mysterio will air on Christmas Day on BBC One at 5.45pm.