The Blue singer, who went to rehab in 2014 after a drink-driving arrest, credited his dance partner Nadiya Bychkova in helping change his relationship with booze.
Speaking to Press Association, he said: “If anything I’ve lost a lot of weight, I haven’t weighed myself but my clothes feel massively different and I just feel great.
“I’ve stopped drinking, I’m on the wagon. It’s good, though, because I have in the past dabbled and struggled and gone to rehab and stuff so I’ve just decided that drink is not good for me and it’s a really good thing (quitting).
“Nadiya really helped, she turned around and said ‘you should just knock it on the head’.
“Everyone has a strand of DNA and mine says ‘I can’t have just one’. I feel amazing for it (stopping drinking).”
Lee continued: “Idle hands make the devil’s work and it’s good to be busy.
“I don’t have time, I couldn’t do this on a hangover, I want this opportunity to be fit, healthy, focused.
“It’s such a good opportunity and it doesn’t come along many times in your life.
“It’s really good for me, it feels like quite a turnaround for my own mentality, which is not just for the show but for me personally as well.”
Lee and Nadiya will be taking to the ‘Strictly’ dancefloor again this weekend, after surviving last week’s dance-off.
The pair had gone up against Susannah Constantine and Anton Du Beke after landing in the bottom two.
Lee later came back fighting in a defiant Instagram post, writing alongside a picture of a rhino: “I didn’t survive in this industry for 20 years now without growing some thick skin like this dude!!
“I’ve been knocked down more times than a bowling pin - it’s how you come back fighting that shows the true strength and character of a person.
“You gotta drag me and @nadiyabychkova out of this show @bbcstrictly !!!”
‘Strictly Come Dancing’ continues with Movie Week on Saturday at 6.30pm on BBC One.