Brendan's parents are avid skiers and got him on a pair of skis for the first time at 2 years old. When Brendan, also known as B-Mack, was 4 years old, his parents signed him up for the Nancy Greene ski group out of Nakiska. This led to a short racing career that ended when the Calgary skier turned 10 years old.

At this point, Brendan's older brother had become bored with racing and wanted to pursue freestyle and freeride skiing. Brendan followed his brother's lead and joined the freestyle club out of Calgary Olympic Park, as well as the freeride club out of Lake Louise.

For the next few years, Brendan competed in lots of different freestyle events, from junior big mountain competitions to moguls events, before eventually making the decision to focus all of his competitive energy into Halfpipe.