I'm walking because my paternal grandfather, my Tachi, suffered from heart disease. I've been told the story of the massive heart attack he had before I was born. It was bad enough that I was never supposed to meet him because it should have killed him. However, I was lucky enough that he survived it, and I had 18 wonderful years with him as my Tachi before he passed away.
Since heart disease runs in my family, I walk to make sure there's enough research and resources to help keep me and my family healthy and taken care of if we ever need it.