See her work out

Professor Green has let slip the secret to Millie Mackintosh‘s slim figure.

The rapper has shared a video of his fiancée completing a tough work-out.

The Instagram clip shows the 23-year-old exercising with a personal trainer.

She powers through a tough routine including lunges, squats and weight-lifting.

Despite looking toned in lycra shorts and a vest, it seems the former Made In Chelsea star doesn’t want to be snapped.

Realising that her man is filming her, she makes a rude gesture at the camera.

#instavid go on bird give it some! @camillamackintosh,’ writes Pro, 28.

Go on bird! That’s what we like to see!

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Kate Lloyd