The 57-year-old musician is quoted by the Daily Star newspaper as saying: “It coincided with my stopping drinking and drugging and turning into Forrest Gump – I would run 18 miles before a gig.
“It isn’t about some redemptive ‘my drink and drugs hell’ – nor is it about abstinence.”
The ‘No Time To Die’ guitarist – who still gets high “once or twice a year” – credits stopping boozing with improving his songwriting.
He added: “If I thought boozing and drugging would make me write better songs, I’d be doing it. But it doesn’t.
“Stopping drinking worked out great. I got more intense and I started writing lyrics I really liked.”
Meanwhile, Marr previously quashed rumours suggesting The Smiths were planning a reunion.
A fan sparked speculation the legendary band – who split up in 1987 – were “closer than ever” to making a return in 2019, but when another fan asked Marr if the gossip was true, he made a quip comparing his former bandmate, frontman Morrissey, who was pro-Brexit, to the leader of the Brexit Party, Nigel Farage.
He simply wrote back on Twitter: “Nigel Farage on guitar.”
Morrissey courted controversy when he said the result of the EU Referendum in June was “magnificent” and he also hailed Farage a “liberal educator”.
Marr later addressed his comments and insisted he has nothing to do with his bandmate’s political opinions and that he doesn’t see the band – which was also comprised of Andy Rourke and Mike Joyce – making a comeback anytime soon.
He said: “I can only really speak for myself, I don’t feel like it’s necessary at all really.
“I really like moving forward. Myself and Andy (Rourke, bass player) play together when I’m over in New York … he plays a couple of songs with me and that’s always really nice, but that’s really as far as it needs to go I think.”