The two singers were spotted running up Tower 42, the second tallest skyscraper in London, in a bid to raise money for Shelter housing and homelessness charity in the Vertical Rush Challenge.
The Vertical Rush Challenge is the tallest and toughest tower race in the United Kingdom, with runners putting their physical stamina to the ultimate test by making their way all the way up to the 42nd floor of the landmark tower.
Just imagine all of those steps!
After some warming up and an intense sprint up the stairs, Lee and Duncan finally reached the top, where they enjoyed an impressive view of the capital.
Is it just us or does Duncan look like he barely exerted himself?!
Ex Celebrity Big Brother housemate Lee is now back in England after a romantic trip to Thailand with love interest Jasmine Waltz.
The pair fell for one another in the CBB house in January and despite hitting a rocky patch on the show and becoming embroiled in a love triangle, they now appear to be making a go of things - although we can never quite keep up!
As well as trying to work out what his relationship status is, Lee is also focusing on his first passion: music.
He tweeted recently: "Can't wait to get back to touring and doing the new album!"
Would you take part in the gruelling Vertical Rush Challenge? Let us know below, as the best comment from across the website each week wins £50!
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