While the very thought of doing exercise for that long makes us feel instantly sleepy, Lucy was actually filming new workouts for her online fitness site Results With Lucy. Panic over!
Instead of a mammoth gym session, Lucy joined forces with her personal trainer Cecilia Harris to film herself demonstrating new exercise techniques for her users.
And in between filming breaks, the brunette beauty made sure to take a selfie with Cecilia!
Most of us wouldn't dream of braving the camera while all hot and sweaty, but Lucy has already proven she looks just as fab post-workout as she does beforehand.
In her snapshot, she can be seen rocking her gym gear with her make-up still perfectly in place. Alongside it she told fans: "Day 3 filming for my website @resultswithlucy .. 8am-8pm filming workouts for 3 days! Eekk!"
Lucy's busy day at work comes after the fitness guru joined her boyfriend Louis Smith in France over the weekend.
Supporting her boyfriend as he took part in the European Gymnastics Championships, Lucy was one proud girlfriend as she watched Louis take home gold!
The Olympic medallist even treated Lucy to his winning bouquet. What a gent.
Following speculation they were dating, the pair finally decided to go public with their romance earlier this year. Since then, Louis and Lucy appear to be pretty smitten with each other.
Louis even told Reveal recently: "Lucy is just so lovely which is rare to find in someone who looks as beautiful as her... I haven't felt like this for a long time."
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