Jaap Kuiper is not only an optician, he has also trained with Wim Hof (the Iceman) in Poland. As a certified instructor in the Wim Hof Method, Jaap regularly gives workshops 'Power through Breath and Cold'. In this simple method with breathing exercise, commitment and cold habituation, you influence your immune system, you become more cheerful and you can combat acidification. Jaap Kuiper also sells barefoot shoes. Walking naturally: a relief for your feet.