I don't know of anyone who has done it for 35 years but most small business owners I know in competitive industries like restaurants work at least 12-14 hours a day, often taking only a few days off a month. Perhaps this has to do with the higher cost of living in their areas but it's pretty well accepted that small business owners and sole proprietors generally work a lot more than regular employees. Due to western labor laws regarding benefits and overtime that is usually the only way they can make it.