On 22 August I'll stand on the shoreline in Tallinn, Estonia, preparing to swim 3.8 kilometres before cycling 180km and running a marathon. It will be the biggest physical challenge I've ever attempted. But however difficult the day becomes, I'll already know where to look for inspiration. I'll be thinking about my friend, Olly Adams.

I only knew Olly during the final years of his life, after becoming friends through his brother George. Like many friendships, ours revolved around football. We followed Aston Villa across Britain and Europe, sharing the unforgettable high of Bruges and plenty of considerably less glamorous afternoons wondering why we put ourselves through eternal torture. What I'll remember most, though, wasn't the football. It was Olly's dry wit, his razor-sharp intelligence and his refusal to surrender an argument, particularly if it involved Aston Villa. Even when you knew you weren't going to win the debate, you somehow enjoyed losing it.

Behind all of that was something that most of us can scarcely imagine. Olly had lived with a rare brain tumour for seven years. There were setbacks that would have overwhelmed many people. Yet he met them with a resilience that was never performative or self-pitying. He simply carried on living. Simply carried on being Olly.

In his final days, his family sat by his bedside watching a Villa match while he slept. Hearing one of them praise the much-maligned Ollie Watkins, Olly suddenly bolted upright.

“He's rubbish!"

Then he lay back down and went straight back to sleep.

Working in health and care policy, I spend much of my professional life thinking about how healthcare systems improve people's lives. It's easy to talk about research, innovation and investment in abstract terms. Knowing Olly made those conversations deeply personal. During the final years of his life, he and his family received outstanding care from the team at the Queen Elizabeth Hospital in Birmingham. Supporting the QE Brain Tumour Fund isn't just about funding research into new treatments. It's about giving families more time together, improving care for future patients and creating hope where, too often, there isn't enough.

There was one final piece of footballing cruelty. Only weeks after Olly passed away, Aston Villa finally ended a 30-year wait for a major trophy. I travelled to Istanbul with his brother George and father David to watch Villa lift the Europa League. It was an unforgettable night, but there was an unmistakable sense that someone was missing. Olly should have been there, probably reminding us that despite the 3-0 win, striker Ollie Watkins was still his usual wasteful self.

Earlier this year I completed my first Half Ironman in Nottingham. Five minutes into the swim I lost my goggles. Soon afterwards the cramp began. I'd love to say I handled six-and-a-half hours of cramp with the same humour Olly showed through seven years of illness. I certainly didn't. But whenever I felt sorry for myself and thought about quitting, I found myself thinking about him instead.

Tallinn will demand far more: nearly 4km in the water, 180km on the bike and then a marathon to finish. There will certainly be moments - as there have been throughout gruelling months of training - when I wonder why I signed up for any of it.

When those moments come, I'll think about Olly. I'll think about someone who kept putting one foot in front of the other through challenges infinitely greater than anything an Ironman can throw at me. Someone who continued to laugh, to argue passionately about Aston Villa, to travel, to enjoy life and to make everyone around him better for having known him. If I cross the finish line, it won't simply be because of months of training. It'll be because one remarkable friend changed the way I think about resilience.

I'm proud to be raising money for the Queen Elizabeth Brain Tumour Fund in Olly's memory.