Secret to a happy marriage?

My grandparents just celebrated their 69th wedding anniversary. They told me that the secret to a great marriage is doing things together as a couple. They camped, fished, poured concrete for a patio and hung shingles on their home, not to mention raising two boys, enjoying 5 grandchildren and 12 great grandchildren! Grandma also reminded me that every Sunday for lunch they would split a margarita!!!