What About the French Fries?

Sage advice dictates that one should plan like you're going to live forever and live like you're going to die tomorrow. Okay, so then what do you do about the French fries? Because if I were going to die tomorrow I'd be having Nathan's French fries with ketchup and salt for all my meals. But if I do that and then live forever, I'm going to be fat and very unhealthy.

It's a quandary.