We've been together since we were 16. Now, at 67, caring for our grandkids is another way we bond.

• Rena Clare met her husband, Denny, at 16. At 67, the couple celebrated 51 years of togetherness.
• They've been each other's only partners and continue to enjoy a healthy love life.
• Clare described the key reasons their relationship is so strong after all this time.

This interview is based on a conversation with Rena Clare, 67, the grandmother of five, a former personal assistant and at-home mom from Kamloops, British Columbia. It has been edited for length and clarity.

My now-husband, Denny Clare, went on an extended summer vacation with his family in June 1979, four months after we first became boyfriend and girlfriend.

The night before he left, we went to see a movie, and he gave me a bouquet of flowers as we kissed goodbye in the car. I went into the house and sat in the hallway crying.

My mom, who was still awake, said, "Are you OK?" I said, "Yes, but I don't really know why I'm crying." She put her arm around me and said, "It's because you're in love."

She was right. Fifty-one years on, Denny and I love each other even more than we did then. We have three children and five grandchildren, and we live a fun retirement filled with activities like hiking trails, traveling, and entertaining.

People often ask us about the recipe for our long and happy marriage. We're an open book and enjoy sharing the secrets of our success.

We celebrate every anniversary, no matter how insignificant it may seem

Denny gave me his high school ring on March 1, 1979, which solidified things.

It might not seem important to others, but we mark the date every year. We'll go out to a restaurant or write a special letter to each other.

In fact, we celebrate pretty much anything. Denny will leave me a note saying "Happy December 1" with little hearts all over it, just because it's the beginning of another month together.

He's very affectionate and doesn't just assume that I know he loves me. We say how much we appreciate each other all the time.

Of course, there have been moments when we've said unkind things, but as we've gotten older, we've realized it doesn't get you anywhere.

We air grievances, but we listen and try to change our approach, rather than yell and get mad.

We do most things together, but take time off

Denny and I share the same interests, especially spending time with our five grandchildren.

They love theme days, so we'll turn our basement into a space lab with foil blankets and blinking lights. Then we'll make jetpacks for them out of pop bottles and paint moon rocks.

It's almost as fun for us to plan this grandkid time — we don't call it babysitting — as it is to do it. We never stop laughing.

Entertaining friends is important to us, and in the winter months, we'll host two or three dinner parties a week. He'll be stirring the soup in the kitchen while I'm cooking the entrée. We split the responsibilities.

That's not to say we don't enjoy spending time apart. Denny volunteers at a local ski hill every Tuesday and shows people around the mountain.

Meanwhile, I'll be at home. doing arts and crafts. It's vital for any relationship not to be joined at the hip.

Now we're in our 60s, we prioritize health and fitness, and our love life

Our favorite joint activity is hiking. We established a website that offers tips on where to go in the Kamloops area and features my photography.

We'll hike an average of eight miles a day, whether it's in shorts in summer or with snowshoes in winter. Our shared philosophy is that life is always better outside.

The exercise keeps us in shape, and we also eat healthily. There are always a lot of fruits and vegetables, and we try to avoid processed foods by making things from scratch.

We want to be able to keep up with each other for a long time yet.

We cuddle at night, and Denny's arms are around me whenever I go to sleep. We were both virgins when we met and have only been with each other. Our sex life is as crazy good as it was at 16.

We take turns to plan romantic trips, whether it's a city break somewhere like Boston or a monthlong wilderness trip in Utah.

Trust comes naturally to us, and a deep sense of love. It's important for both people in a good relationship to remember how lucky they are.