Peter Capaldi has said he was worried he would have started “phoning it in” if he had continued his role in Doctor Who.
The actor, who took over as the Time Lord in 2013, announced in January that he would leave the BBC show in the 2017 Christmas special.
Peter, 58, told The Sunday Times: “I was not sure how long you could keep doing this and be doing your best.
“My fear was that if I went on, I’d end up phoning it in.
“Because there’s so little preparation time, you’re mostly flying by the seat of your pants – which is exciting, but I worried I might not be able to keep on doing it as well as I’d like to.”
The actor – who previously said playing the Twelfth Doctor had been “cosmic” – has not decided what to do after his time in the Tardis comes to an end.
“Filming Doctor Who has been so all-consuming,” he said.
“I haven’t been out in the world to get a job. I’m about to face all that.
“And of course it pushes all your buttons, all your old anxieties come tearing back, but you hope that more fame affords you more choice.
“But actually I have no idea.”
However, the actor – who is also known for playing spin doctor Malcolm Tucker in BBC comedy The Thick Of It – said he is not after “another political thing”.
“I’ve done enough of that, being a man in a suit shouting at other men in suits,” he said.
“I want to do something different, with a big wig. I want to get dressed up!”