Jimmy Carter and Wife Rosalynn Reveal Secrets to 75-Year Marriage — Including 'Plenty of Space'

Jimmy Carter and wife Rosalynn are touching on some important ingredients to their happy relationship as they celebrate 75 years of marriage this week.

In an exclusive interview with Good Morning America, the 39th president of the United States, 96, and former first lady, 93, recall the beginnings of their relationship and share some of the secrets behind how they have weathered the storms of the past 75 years together.

"We've survived this long together because first of all, we give each other plenty of space to do our own thing," said President Carter.

It works, he added, in part because they "share as much as [they] possibly can" when it comes to their interests — like making fly fishing around the world "a major part of [their] recreation."

"We're always looking to do things or find things we can do together, like fly fishing and bird watching and just going out to the pond, catch a fish," Mrs. Carter said.

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Another part of the couple's connection is reading the Bible together every night for the last 60 years — even when they're apart from one another — and trying not to go to bed feeling angry at each other.

"When I'm overseas and Rose is at home, we know we're reading the same biblical text, and even though we're separated physically, it makes us think about the same scripture and admonition from God, direction from God, before we go to sleep," President Carter said. "So it helps a lot."

The Carters, who are the longest-married presidential couple in U.S. history, have "always gone deeper in our love for one another," President Carter said — which is something he thinks is "extraordinary."

"Doesn't happen to very many couples, but it certainly happened to us," he added.

Back in May, the couple's grandson Jason Carter told PEOPLE that his grandparents are planning a "big party ... with a lot of their friends from over the years" in their hometown of Plains, Georgia, this month to celebrate their milestone anniversary.

"The number of things that have to go right in your life to have a 75th anniversary," said Jason, 45, "it's a truly incredible milestone."

In their conversation with GMA, the couple shared that the party would be held at a school in Plains, and that President Carter gifted his wife a diamond necklace last month with a "75" design on it that she hasn't taken off since receiving it.

"We've got everything arranged so we can accommodate a big crowd," he said of the upcoming celebration.