How can I convince my husband, gently yet effectively, that he is not getting any younger...hence needs to?

Schedule an off-time every day, e.g. dinner and evening. I have the opposite. I need to schedule a work time or I won't do any. As for health, it's all in the mind. If his mind is peaceful, he can do what he likes. If not, he needs to take timeouts to reset and start fresh.