Far from being an Olympic swimmer or an adrenaline junkie, Henrikson works as an organizational psychologist and runs workshops on leadership or gives talks about staying motivate on the job for companies and their employees.
So just why does he lower himself - without a wet suit mind you - into freezing cold water?
This brave experiment all started 157 days ago, back when it was a lot warmer. Swimming always brought back good summer memories for Henrikson but what he was interested in was habits and how we get new behaviors to stick.
Henrikson read an article by a British psychology researcher that sought to figure out just how long it actually takes to form a habit. The answer? On average, it takes 66 days for a new behavior to become automatic.
And with New Year's Day just a little more than 3 weeks ago, that means people struggling to keep their New Year's resolution still have some ways to go. And Henrikson has some advice for that.
"The most common mistake that people do is that they go too big. So just break it down," he tells Radio Sweden. "Make it small and achievable and when you manage that, then you can grow the habit."
His experiment though has gathered some mixed reactions from friends and family. And Henrikson stresses that he doesn't take unnecessary risks while going for dip.
"Mom has gotten a little bit worried now, during the winter," he says, "so I'm telling her that I'm very careful around the ice and have safety routines."