THEM: You have a long marriage. What is your advice?
ME: No idea. Go with the flow. Be as different as possible in your habits, but the same as possible in how to live life.
For example:
He eats meat (a lot), you don't.
He makes the bed, you - not so much (only under duress and after a disapproving look).
He stacks the dishwasher like it will be inspected by the Dishwasher Committee. You just throw things in there in the hope they will get properly washed.
His nightstand looks neat, while yours looks like a rabid dog went through it.
He is calm, while you are a volcano ready to burst at any given moment.
He is a calm driver (very different from when you first met), while you got your driver's license at thirty something (because there was no way out of it) and now your driving is a bit out there.
THEM: Huh?!?