Excellent point I had not considered. I'd still be curious to see whether those signed up for cryonics have healthier habits (with respect to exercise, diet, wearing bike helmets, etc.), but this seems like reasonable evidence to believe they do. In fact, it seems to me that signing up for cryonics, even if you believe it to be overwhelmingly unlikely to work, might provide strong incentive to have good habits. I don't know if this is cost effective, but it's worth considering.