Kyokushin Karate

Well it has been almost a year since my son and I started this style of Karate and we are both really enjoying it. It keeps us fit and I just love the kata. My son enjoys it too and he is keen to get his black belt one day. I'm not sure if I will be able to cope with the physicality of a first dan grading. I'd love to hear from others who do this or other styles of karate. Why do you do it?