Op described a situation where his parents are struggling to run the business and it is taking a large physical toll on them as well. They aren't "enjoying themselve" they're working themselves to death. All to many elderly people are staying in the workforce because of fear of not having enough money or nothing to do without work but it's all nonsense. They have a business they can sell and walk away with enough money to enjoy their remaining years, spend time with their grandchild and live and enjoy life. I'm all for hard work and a strong work ethic but self destructive working habits are dangerous, you should own your business not the other way around.