Straight from the horse's mouth.

When you walk down the aisle and exchange vows, you can only hope that your love and wedded bliss truly lasts forever.

But there are never any guarantees. There's no better way to figure out the secrets of love than from happily married couples who are going 50 years strong.

It's an amazing feat to find that one special person that you will spend the rest of your life with. And once you do, you never let them go.

It can be hard to open up and let yourself fall in love, but when you find a soulmate-level connection, you won't have to try with them — it will just happen naturally.

When you look back at your love 50+ years later, you will still remember when you first fell in love. Because you just don't forget something as special as that.

Author Laura Fleishman published a book called The Lovers, which features a series of love letters between her grandmother and grandfather during World War II.

She also interviewed other older couples — all married 50 years+ — and found out what they had to say about love. Here are three beautiful secrets about marriage they shared.

1. Support each other's interests.

“David always supported any interests I had. He supported me with whatever I did, told me I should do the best I can.

And I was anti-intellectual when I married him. I got to love music because he practiced a lot and I listened to him — he explained everything. We really changed, we enriched each other's lives." —Sheila Newman, married in 1957

2. Expect your love to change.

“In June, we celebrated 74 years of marriage. But I never think of it in terms of years. I think of it in terms of good years. In love, hot romance doesn't last forever. So I would say that yes, I think love changes.” —Dorothy Bolotin, married in 1938

3. Sometimes you find love with someone you least expect.

"I was the kind of girl that I fell in love right away. So the next day, I would tell my friend, ‘Terrific, I mean, I'm in love already.'

But after the first date with Sol, I did not feel that way. I told my friend, ‘No, he was very nice. We had a good time, but that was it.’ She was the one that came back with the statement, ‘I bet this is the guy you're gonna end up marrying!’” —Gloria Holtzman, married in 1954

Making love last is not always a picnic, but these couples are reminders of what it looks like when you stick around through the hard times.