In an interview with Empire, Whittaker talked about stepping away from the character she has played since 2017 and the emotional impact of her regeneration scene.
She said: “I love the dialogue Chris [Chibnall] wrote for my regeneration. It captures my Doctor beautifully. It’s simple, epic and beautiful. When I could see the crew was happy with that last shot, that’s when my bottom lip started going.
"I was like, ‘Well, they can’t say they need another take now because I’ve f*****g lost it!’”
Whittaker also talked about what Doctor Who fans can expect from her final episode which airs later this year: “It’s a huge treat if you’re a proper fan. It’s got all the iconic things that you associate with Doctor Who. It’s massive.”
With Whittaker departing the show, she is set to be replaced by Sex Education star Ncuti Gatwa who will appear as the Doctor for the show's 60th anniversary specials which will air next year.
Russell T Davies is also returning to the show to replace Chris Chibnall after originally writing Doctor Who from its revival in 2005 to his departure in 2010.
Read more: First look at Doctor Who special
Before he died in July, Bernard Cribbins, who previously appeared on the show as Donna's grandfather Wilfred, filmed scenes for the specials.
New castmembers for the anniversary include How I Met Your Mother star Neil Patrick Harris and Heartstopper actor Yasmin Finney who will play a character called Rose.
Jodie Whittaker's last episode – The Power of the Doctor – will air on BBC One in October.
Watch below: Russell T Davies promises Jodie Whittaker's Doctor Who exit is 'gorgeous'