Warning: This article contains references to suicide. If you ever see Mr Luke Yeo out and about, you may find yourself wanting to give him a wide berth. At first glance, the 33-year-old is physically intimidating, his hulking frame covered in tattoos and broad shoulders bulging with muscle.It is a look he has worked on since he was a teenager – back when he was known as the "monster" of the gang he was in. "When you get into fights, you have to be bigger than someone or you learn how to fight. Or you have to be daring enough to use a weapon to hit somebody," said Mr Yeo. "The best way was to train to get size, so nobody would want to fight (you)."Almost two decades later, what started out as a bid to build a reputation for being a fearsome gang member has evolved into his life's work as a competitive bodybuilder and owner of Unstoppable Fitness, his four-year-old gym in Shenton Way. I'm not generally one to judge a book by its cover, but when I first met Mr Yeo over a video call, I wasn't quite sure what I would have in common with a gym owner whose physique takes up a good portion of the frame. Admittedly, I grew up bookish, and was a reluctant entrant to the fitness scene only as an adult. But right away, Mr Yeo shared that he too started out as a skinny teenager. At 13, he was already being bullied for looking "like a stick", standing at 1.68m tall and weighing 42kg – about half what he weighs now.He would go on to run with a gang, drop out of secondary school and, at his lowest point, spend time in prison, before discovering in the gym the camaraderie he had once sought in the wrong places. During our second meeting at his gym, this time in person, I was nursing a cold and feeling a bit out of place as mostly male members around me moved through their sets, the occasional clang of weights and grunts of effort punctuating the high energy music pulsing through the speakers. When I raised the "alpha male" or "gym bro" culture sometimes associated with certain fitness spaces, Mr Yeo said that he understood where the stereotype comes from and that gyms once felt intimidating even for him. In his experience, however, it is often the "biggest guys", covered in ink, who are the most willing to help a stranger in the gym.