Mikulak grew up watching his older brother and his friends play on a pond behind his house. From a young age he had always wanted to play with them and so he trained as hard as he could, eventually he was good enough to play with them, usually subbing in for whatever position they had a hole in, whether that be a winger, defenseman, or even goaltender, though he only played as a goalie on a few occasions and never played centre due to his smaller size. Eventually his size and speed would lead him to be a winger every time he played. His skills playing against players who were older and larger than him eventually got him on his first junior club and from there he ended up being scouted for the SMJHL and drafted in the 4th round of the S45 SMJHL Entry Draft by the Vancouver Whalers. Which put him on the path of becoming an SHL Star.