For most people, playing professional sport would be enough to keep them out of trouble. But throughout his playing career, Brown kept the idea of a career in design ticking over. In one of his off-seasons, he took a pivotal fact-finding trip in China.
"I found a footwear factory on Google and thought 'I'm going to dive in'. In the off-season, I took a trip and started visiting footwear factories. It was like woah, this industry is massive, it's enormous, and it's incredibly manual and basic. It defaults to using really cheap materials and isn't there an opportunity to do things a bit differently."
From there, he decided he'd be guided by three principles: design, comfort and sustainability.
Brown battled through the initial stages of building Allbirds; coming up with prototypes and having to develop a shoe to give to people who invested in his wildly successful Kickstarter campaign.
But it was taking its toll, and he was ready to quit, before meeting co-founder, Joey Zwillinger. Their wives had been roommates at college, so they met to discuss where Tim was at. Over a couple of days, they created the future of Allbirds.
"We just imagined this business. And I think really importantly, (we) imagined a business we would tell our grandchildren about. I think I found in Joey, and his vision around the environment and climate change, I found the purpose that had been missing up until that point.
"I'd been making shoes, making them out of wool and those were really important things but if you're going to go over all the hurdles you need to, all the pain, all the hard work, it needed to be for something bigger."
They were still based in Joey's mother-in-law's garage, but they'd raised $2 million in seed funding, and Tim had renewed focus on his goal on making sustainable footwear. They were still being told that their strategy of just selling one kind of woollen shoe, and only selling online, was impossible.
"And I think it was a real test of our philosophy. We stuck to our guns. We launched one shoe. You have these moments where you have to back yourself."
To find out how Tim Brown and Joey Zwillinger took the business from a garage operation to billion dollar operation, listen to HP Business class here