Donald and Vivian Hart of Grand Rapids, Michigan, know a thing or two about nurturing a long and happy marriage.

The 99-year-olds celebrated their 80th wedding anniversary. The couple, reminiscing on their lives together, shared words of wisdom on how theyโ€™ve kept the spark alive.
โ€œItโ€™s good to laugh together,โ€ Donald, a World War II veteran, told ABC News during a family celebration of the major milestone. โ€œHave fun with each other, but donโ€™t make jokes at the expense of the other.โ€
โ€œAlways be sure to put God first in your life,โ€ Vivian added. โ€œBe always willing to help and stay alert to your spouse … We donโ€™t keep our mind on our troubles.โ€
At their anniversary celebration on Friday at the assisted living facility where they live, he serenaded his wife with that love song once more. โ€œLet me call you sweetheart,โ€ he crooned. โ€œIโ€™m in love with you.โ€
Speaking to local media, the coupleโ€™s children remembered their parentsโ€™ love and commitment even through years of hardship.

Vivian and Donaldโ€™s family claim they are the longest-living couple in the state of Michigan. The lovebirds tied the knot in 1937.

Donald and Vivian have three sons, four grandchildren, 14 great-grandchildren and 15 great-great-grandchildren, according to the localย WDIV-TV.