Stanglwirt is a sprawling bio-hotel located in the Austrian Alps and which at first glance looks like the setting for a slow-burning, creepy horror movie. With its mountainous background and somewhat kitsch interior – heavy wood panelling, stripy sofas – it brings about memories of the Overlook Hotel from Stephen King’s The Shining. Walk through the lobby, past the staff dressed in lederhosen, and it feels like only a matter of time until a clock goes off, a cuckoo springs out and a body falls down the stairs.

But on this spring visit there is no horror to be had. Instead, amid the restaurants and bars, the spas, saunas and swimming pools, resides a story of redemption. Or, as Wladimir Klitschko puts it, fulfilling an obsession.

The heavyweight is here to prepare for his bout with Anthony Joshua at Wembley Stadium on 29 April. Stanglwirt has been his pre-fight base since 2003 and a place he describes as a “home away from home”. It is easy to see the appeal – for all its “Here’s Johnny!” qualities, the complex, now more than 250 years old, is a beautiful place to spend some time. Pristine, picturesque, warm, friendly and with plenty to do and consume. For Klitschko it is somewhere to get his mind and body right, which now more than ever is important for a boxing great who, as he admits, is about to take on a career-defining challenge.

Klitschko has not fought since his shock defeat to Tyson Fury in Düsseldorf 17 months ago. It was an outcome that not only stripped the Ukrainian of his WBA, IBF and WBO titles but also of his cloak of near-invincibility. Dr Steelhammer, a fighter who had secured 53 of his 64 victories across a 27-year career by knockout, was outgunned by a man who dressed as Batman for one of their pre-fight press conferences. Fury was a joke, yet after a unanimous points decision on 28 November 2015 he was the one laughing.

Much has happened to Fury since that night and one of the consequences has been Klitschko missing out on a rematch that would have provided him with a chance to prove he is no busted flush after a fourth defeat since turning professional in 1996. “Unfinished business,” as he puts it. Now, finally, comes the chance for him to go again against a British fighter.

Wladimir Klitschko and his physio Aldo Vetere at the Stanglwirt hotel. Photograph: Johann Groder/AFP/Getty Images

Joshua, the IBF champion, poses a different threat to Fury – a year younger at 27, stronger and more deadly. Then there is the setting: a stadium Klitschko has never fought at, in front of a 90,000 sellout crowd. He goes there on the back of his longest period of inactivity since first lacing up a pair of gloves, and having just turned 41. Little wonder this most assured of men is full of questions, full of doubts, as he spoke at Stanglwirt.

“This fight is 50-50,” Klitschko said. “Can the younger guy make it? Has the older guy still got it? Question marks are making this event really interesting. I’ve never had a pause for a year and a half. Is it bad? Is it good? Will I have rust? I want the answers myself.

“One thing I believe is I don’t feel my age. It’s not empty words. I am getting in the best shape of my life, physically and mentally. I don’t see I’m stuck and not improving, even in a sport I’ve been involved with for so long. That’s what interests and excites me.”

Funeral or hospital? Hospital or funeral? I don’t need many punches to knock a person out Wladmir Klitschko

Klitschko certainly looked well as he spoke, flanked by his manager, Bernd Bönte, and his trainer, Johnathon Banks.

The body remains imposing and defined, his face chiselled and those hands continue to look like weapons of mass destruction. Asked to predict how the fight with Joshua will go, Klitschko raised his fists and nodded towards them in turn. “Funeral or hospital? Hospital or funeral? I don’t need many punches to knock a person out.”

That was a rare moment of trash-talking bravado from the veteran (alongside the moment he claimed Joshua gets confidence from his muscles and is better suited to bodybuilding).

Generally Klitschko was respectful of his opponent, borne partly out of the fact Joshua goes into their fight on the back of a perfect professional record – 18 wins from 18 fights, all achieved via knockout – and partly because of the respect Klitschko developed for the man from Watford, having invited him to be a sparring partner in November 2014, before taking on the Bulgarian Kubrat Pulev.

“He impressed me with his attitude,” Klitschko says. “He was in the background and learning. Sometimes you need to be quiet and just watch, and he was observing everything. He could also box, so I gave him credit and I was there in the arena when he won gold [at London 2012]. Every medallist in the super-heavyweight division at the Olympics has to be considered successful. He has a lot of potential and so far has done good.”

Unlike Fury, Joshua is likely to engage with Klitschko from the first bell, looking to plant his feet and unload bombs as often as possible. On one hand that provides the challenger with a standing target – not to mention a supposedly vulnerable chin – but on the other it means he will have to engage himself, something Klitschko did only in the 12th round of the Fury fight when his uncharacteristic hesitancy against a moving target had given him no choice but to go for broke. Ultimately it was too little, too late.

Klitschko insists he has learned from his mistakes and will be fully prepared for the challenge by the time he arrives in London on 26 April. Until then it is a case of working hard and staying focused, something that was there to see at Stanglwirt.

The scene was a converted tennis court in the bowels of the hotel. In the middle stood a ring while at one side were three punchbags hung in ascending order and at another a basketball net where, at around 8am, Banks shot hoops with another member of backroom team as Klitschko went through a series of stretching exercises. Two television screens had been set up showing Joshua’s previous fights, everything taking place to the sound of Motown classics. It was a relaxed start.

Banks and Klitschko eventually underwent some pad work inside the ring. It was, in keeping with the mood of the morning, a relatively gentle session but the sound of thudding fists carried enough of an echo to remind onlookers of the power coming Joshua’s way later this month. The 27-year-old is the favourite with most bookmakers but complacency would be foolish against a man who has been there, done that, and is entering the ring not because he needs the money but because he is determined to remind the world he remains one of the most durable heavyweights and, yet again, has what it takes to be a champion.

Wladimir Klitschko was uncharacteristically hesitant against Tyson Fury in 2015. Photograph: Kai Pfaffenbach/Reuters

“Failure is an experience and I’m coming after a defeat [against Fury] with a totally different attitude,” Klitschko says. “I learned more about myself, about boxing, through that defeat. Unfortunately I cannot change it, or have a second shot like in golf – there’s no mulligan for me. But I’m not a destroyed man.

“This may sound arrogant but I am like Mount Everest. You can climb it during a certain period of time – during two weeks in April I believe – and say: ‘I conquered Everest.’ Then you’ve got to run down because it’s going to take you down if you miss the time.

“Some make it back but a lot of people die, so is Mount Everest defeated? No, it’s still there and it’s going to take another life this April.”

Sky Sports Box Office will show Joshua v Klitschko exclusively live on 29 April. To book go to www.skysports.com/joshua