Trying to say a word that was difficult or "blocked" made speaking even harder.
"If I started to say something that was blocked I would stutter and become out of breath, and associated with that was a lot of fear. I actually felt quite afraid."
He said his stutter got so bad that at times he would tremble and shake. "I wouldn't play any team sports at school - I'd do tennis or rock climbing because they were solo sports and involved no communication.
"Growing up and trying to choose a career I would think of things that involved no communication, so I would look at solitary careers like chefing or something - jobs that involved no interaction.
"I would pick the type of activities I would be involved in, or the types of sports or friendships I would have, because I would try to fit in around the problem."
Although he received speech therapy as a child, it was not until about 10 years ago, when he completed a course called the McGuire programme, that he began to overcome his stutter.
A big part of the programme was learning not to worry about what other people thought, Mr Mischefski said.
"I just felt so empowered and relieved, and I knew there was finally an opportunity to break free."
During the four-day course he learnt new breathing techniques as well as how to project his voice.
Tackling his stutter had helped him to get the job he wanted, he said.
"I'm more assertive - if I don't agree with something I'll speak up. I'll ask for directions, I can make small talk.
"If I'm ordering in a cafe I'll chat in the shop - before there was no chance of that."
Mr Mischefski now works in procurement at the Ministry of Foreign Affairs and Trade.
He still tries to improve his speaking, taking refresher courses and keeping in contact with friends from the programme.
"These days I'm a very different person - I'm a lot calmer ... I'm more chilled out, I can let go of things.
"If something troubles me I can just go 'oh well'."
And he now has the confidence to read bed time stories to his 3-year-old son.
"I read to him every night ... it's the everyday things we take for granted."