Today, Jimmy Carter and his wife Rosalynn celebrate 70 years of marriage. The former president says he knew Rosalynn was the girl he was going to marry after their first date. Seven decades later, its clear hes still very much in love. Whats their secret?

She was the right person. Thats the first thing, Carter tells Oprah in the above clip from his SuperSoul Sunday interview. And then, we decided fairly early in our life to give each other plenty of space. Rosalynn has her own ideas, her own ambitions, her own goals in life, which, in some ways, are different from mine. I let her do her thing; she lets me do my thing. And we try to resolve our inevitable and fairly frequent differences before we go to bed at night.

And I think reading the Bible at night helps with that, Carter adds.

Though they give each other their independence, Carter says its important to never stop experiencing things as a couple. We try to find all the things that wed like to do together, he says. Sometimes things weve never done before.

Downhill skiing, for instance, is a hobby the Carters picked up later in life. I was 62 years old before I ever put on a pair of skis, he says. And we are avid fly fishers. Thats our main source of recreation.

When they lay their heads down at night, Carter says their pillow talk is mostly about family. Together, the couple raised four children: Jack, Chip, Jeff and Amy. We have not only our four children, but we have 12 grandchildren and 10 great-grandchildren now, he says.

In fact, in the 2008 election we had 22 voters, Carter laughs.

More: Why Jimmy Carter says he could absolutely not be president today.