Brisbane father John Alexander weighed 178 kilograms, ran out of breath while playing with his daughter and faced a future of health problems. Then he decided to buy a second-hand bike online for $350.

The chef has lost 58 kilograms in two-and-a-half years and now cycles a 70-kilometre round trip to work several days a week.

Tingalpa chef John Alexander turned his life around after buying a second-hand bike.

Last year, he finished four triathlons.

"I started walking around the block before and after work and progressed on and bought my first bike off Gumtree for $350," he said.