If you ask John Henderson what the secret to a long and happy marriage is, he'll tell you it all has to do with two simple things: "Live life in moderation and be cordial to your spouse."
Why does John's opinion matter? Well, if there's anyone you should trust to give you the right answer to that question, I think it's definitely someone who's been with the same person for nearly 80 years.
In fact, I'd go so far as to say they're the only person you should ever ask.