Sven-Goran Eriksson has revealed he has “at best a year left to live” after being diagnosed with terminal cancer.

Eriksson collapsed while on a 5km run last year, which prompted doctors to investigate. They told the 75-year-old he had suffered a stroke, and subsequently discovered advanced pancreatic cancer. “They don’t know how long I had cancer, maybe a month or a year,” the former England manager told Swedish radio station P1.

“Everyone understands that I have an illness, that is not good. Everyone guesses it’s cancer and it is. But I have to fight as long as I can. [I have] maybe at best a year, at worst a little less, or at best maybe even longer. You can’t be absolutely sure. It is better not to think about it.”

Eriksson had been working as a sporting director for Swedish side Karlstad and stepped back from his role.

He said he is trying to maintain a positive mindset. “You can trick your brain. See the positive in things, don’t wallow in adversity because this is the biggest adversity, of course, but make something good out of it.”

Eriksson added: “I was fully healthy and then I collapsed and fainted and ended up at the hospital. And it turned out that I had cancer. The day before I had been out running five kilometres. It just came from nothing. And that makes you shocked.

“I’m not in any major pain. But I’ve been diagnosed with a disease that you can slow down but you cannot operate. So it is what it is.”

Eriksson’s long management career took in Swedish side Gothenburg, Portuguese giants Benfica, a host of Italian clubs including Roma and their city rivals Lazio, as well as Premier League sides Manchester City and Leicester. He also coached Mexico, Ivory Coast and the Philippines, but is most famous in Britain for taking charge of England’s golden generation.

David Beckham, Steven Gerrard, Frank Lampard, Paul Scholes, Michael Owen, Rio Ferdinand, John Terry, Ashley Cole, Gary Neville and a prodigiously talented Wayne Rooney made up one of England’s most talented ever squads. However, Eriksson could not steer them past the quarter-final stage of a major tournament, across a six-year stint which took in the 2002 and 2006 World Cups either side of Euro 2004.

The manager was criticised for his tactical inflexibility, sticking to a rigid and unambitious 4-4-2 which failed to get the best out of England’s star players, at a time when other European nations were developing more sophisticated possession play. Other reasons put forward for England’s failure to win a major trophy were the lack of balance in the side, with an overflow of quality in central positions, and the factions within the squad owing to their Premier League rivalries.

Rooney expressed his sadness and support for Eriksson. The teenage striker burst onto the scene at the 2004 European Championship, having been handed his international debut by Eriksson the previous year, and he was rocked by the news about his old coach.

“Sad news this morning,” Rooney tweeted. “Thoughts are with Sven Goran-Eriksson and his family. A brilliant coach and a special person. Loved and respected by everyone. We’re all with you Sven, keep fighting.”

Rooney’s 120-cap haul is second only to ex-England goalkeeper Peter Shilton, who never played under Eriksson but expressed similar sentiments. “Very sad news to hear of Sven’s illness,” England’s appearance record holder said. “He’s a real gentleman and a great manager.”

The England national team’s X/Twitter account said it was “sending our love, Sven”, while former clubs joined in expressing their best wishes to the Swede.

Manchester City said everyone at the club is thinking of Eriksson and “we wish to express our collective support to our former manager, and his family and friends, during this time”.

Leicester said: “We are all with you, Sven” and Notts County posted that they are “sending love and strength to our former director of football, Sven-Goran Eriksson”.