I want to live a life that is both happy and long. If I have a structural disease that could be fixed with an operation - for instance a cancer or an aortic aneurysm - I'd like to know whether my long and happy life is more likely with or without surgery. And I don't just want to know whether I'll be alive or dead in 30 days, which is the most common published metric of surgical success or failure. I have developed a tool that accurately predicts survival years after repair of abdominal aortic aneurysm and that helps patients decide whether to have surgery or not. The tool also explains how one piece of research has been misunderstood, a misunderstanding that has resulted in two general mistakes: surgeons operating on aneurysms when they should not; surgeons not operating on aneurysms when they should.