Will took part in the BBC One series in 2016 but pulled out just four weeks into the live shows.
He said at the time: "Unfortunately, I am leaving the show for personal reasons.
"I leave with joy in my heart that I have been able to take part in one of the most loved shows on British television."
There were all sorts of rumours about why Will had quit, but in a candid interview he's revealed what really went on.
Opening up about battling severe anxiety and depression, Will confessed he was desperate to get out of the show.
"Mental illness is mental illness. I was unwell," Will recalled to the Daily Mail's Event magazine. "In the weeks leading up to Strictly, all I could think about was how could I get out of doing the show."
He went on: "I knew I didn't have the strength, that I wasn't in the right place and that I would do myself real damage.
"I actually looked into the easiest way to break my legs so I couldn't dance. That’s how bad it was."
Will previously dismissed rumours that he had quit following a row with then head judge Len Goodman.
"It was important for me to leave Strictly for my own wellbeing," the former Pop Idol winner said (via The Sun). “It was a number of things. It was nothing to do with the people on the show, and it certainly wasn’t because Len Goodman dissed my salsa – I mean, come on!
“I love dance, and because of the stuff that was going on personally, I just wasn’t enjoying the dancing.”
He went on: "I was really ill. I was dragging myself to rehearsals.
“I just couldn’t do it any more. It was so bad I thought – I’m not joking – I thought about breaking my leg. I decided to take on Strictly because I bloody love dancing. And I bl***y hated it, because I was so ill.”
Will is currently appearing in the new Strictly Ballroom Musical.
Strictly Come Dancing returns to BBC One in the autumn.