Now here's some post-Christmas workout inspiration...
Although the 36-year-old singer is currently performing on stage as Grizabella in the revival of Cats, she still makes time for exercise, even if she does finder it harder than she used to.
"[Exercise] changes everything about how I approach my day and helps me go about life with confidence – that's the main reason I do it," she explains in her interview. "It gives me clarity and makes me feel stronger. It's not so much for the physical and vanity side of it. I do it more for the emotional and mental strength it gives me."
However, as many of us know too well, getting up and going to the gym can be a challenge.
"For many years I worked out every single day, but now I'm in my thirties it's like pulling teeth. I gotta make myself work out – you need to find that balance," Nicole says.
As for healthy eating? She's found it more difficult to turn down a cheese toastie since moving to London for work.
"I'm working with Sir Trevor Nunn, who used to be artistic director of the Royal Shakespeare Company, so I want to give it my all," Nicole says. "But when I finish work it can be really hard to eat healthily – when it's cold you just want to eat a melted-cheese panini and soup. I'm going to turn into a cup of tea and a curry by the time I leave London! I eat differently in the UK from when I'm in LA. Over there, I'm happy eating a kale salad and sushi rolls but with this weather I've been eating a lot of curry. I do miss the sun in LA, but London inspires me in a different way. It's like being in a movie."
Ready to hit the gym?
More from Nicole below...