Well... considering the exact phrasing "You know you've passed your use-by date for cruising when..."
The use-by date on products is someone else's recommendation
on when the product is past its prime. Doesn't mean the product has gone bad or is now a danger
So... what others think about when I should stop sailing/cruising/anything? Don't effing care.
When should I stop sailing/cruising? Very simple. When I can't do it anymore, or don't want to.