'Fitness freak' Cynthia Erivo wore her fitness watch underneath her Wicked costume

Cynthia Erivo wore her fitness watch underneath her Elphaba costume on the set of 'Wicked' to ensure she got her daily steps in.

The 37-year-old actress plays the Wicked Witch of the West alongside Ariana Grande's Glinda The Good Witch in the two-part big-screen adaptation of the Broadway classic and the self-professed "fitness freak" admits nothing was going to stop her achieving her daily step count whilst filming the fantasy film.

Speaking on 'WTF With Marc Maron', she was asked if she had her Fitbit on underneath her witch ensemble and she replied: "Yes."

Asked if she checked it, she said: "I did. I am not even joking. I am being so serious."

"I had it on me all day. I can either put it in my boot by my ankle, because that is where my pulse is, or I put it on my hip."

Even on her break, Cynthia didn't sit still.

She said: "You are just trying to get the steps in full-stop. If we are on a break, I am not sitting down I am getting my steps in."

Cynthia admits being on movie sets can make you "sedentary" so she tries to keep on the move as much as possible.

She said: "That's the thing on set sometimes, you can fall into being really sedentary and just not moving and waiting."

The Tony Award-winning star recently revealed that she didn't go to the bathroom at all when she was in her costume.

Speaking on the Broadway Podcast Network's 'Wicked' podcast, 'Sentimental Men', she said: "I don't go to the bathroom."

"Once I'm in that costume and this is probably a terrible idea and the harness is on, I'm not doing it. I'm not dealing with it. There's too many layers. I'm not dealing with it. I'm not going to the bathroom. It is what it is."