Flashing plenty of tanned skin, you'd never have guessed it was four degrees and snowing outside!
The former TOWIE star turned fitness guru, 23, met fans and signed copies of her new book Be Body Beautiful at its launch.
Arriving at the book signing at a WHSmith store in Sheffield on Saturday (17 January), Lucy stunned in a bright orange one-piece.
She may have felt chilly, but she certainly didn't look it!
In fact, the Tumble star looked absolutely gorgeous in the cutaway outfit with shorts.
After setting up her own clothing boutique and fitness website Results With Lucy, the stunner has just released her very own book based around the lifestyle changes she has made.
She recently told us that she loved putting the book together, saying: "It was really nice writing it and I think it was good for me because, although my nutritionist and trainer have done a six week plan in it, I wanted people to trust in me as well.
"I'm not a nutritionist or a personal trainer, but I'm a normal girl like whoever is reading the book and in it is what has happened to me - how I've come out the other end and the life changes I've made. It's not pushy at all, it's just about changing one thing at a time, that's what I did. Making those little changes make a really big difference."
As well as becoming a successful businesswoman, Lucy also has something else to smile about at the moment...
She has found love with (rather handsome) Olympic gymnast and Strictly Come Dancing champion Louis Smith.
The pair met on BBC1's Tumble last year and are clearly smitten...
Would you buy Lucy Mecklenburgh's new book? Tell us below and you could win £50!
Reveal is now on Google Plus! Join us here for the latest pictures, fashion and celebrity news!