OK, I’ll bite. In countries that have implemented single-payer, the system is often funded in part by an increase in taxes on unhealthy items such as alcohol, cigarettes, and junk food. This helps reduce the country’s healthcare costs in addition to accruing revenue for the system. However, when you get talking about “forcing” people to exercise and eat better, I wonder how you’re imagining we could ever enforce such a system? How would one determine which health issues were caused by behavior and which ones weren’t? How would anyone prove they weren’t eating fries? I also think you’d be hard-pressed to find anyone who’d be in favor of this kind of restriction of freedom. “The moral justification for this is that somebody must pay for the sick, so why not the well?” This doesn’t really feel like an honest explanation of insurance. The purpose is to spread costs of the few over the many such that individuals are paying a manageable amount and everybody can get care as they need it. You’ll benefit someday too. Everyone dies of something.