Scientists say it can send you into an endorphin-induced state of bliss.
So it makes sense that such an activity -- exercise -- can benefit your relationship with your significant other.
In honour of Valentine's Day on Friday, here are four couples to explain how a mutual love for physical fitness keeps their passion for each other alive:
Uche and Kary Odiatu
Their fitness fame: You might recognize them as the outspoken, peppy and chiselled pair with a knack of inspiring others to get fit. This fitness power couple started their competitive bodybuilding careers in Winnipeg and moved to Toronto more than a decade ago. Today, they are motivational speakers, fitness coaches, authors and parents. Uche is also a dentist.
Relationship status: Married for 15 years.
How they workout together: They've weight-trained together up to four times weekly. They also have a history of taking active vacations. "Instead of just sitting on the beach drinking mai tais, we went into the jungle on our honeymoon propelling on ropes and stuff," says Uche, 50. Today -- with their three young children to care for -- they tend work out solo much of the time. But exercising together is still a treat they try to sneak in as often as possible.
Why fitness is so important to them: "It made (our) relationship very strong very quickly," says Uche. He believes the feel-good chemicals that flood the body while exercising with his wife play a role in their need for physical activity -- and their love for each other. "Your brain is releasing all of these very exciting hormones that makes you even more attracted to the person -- and the event that brought it about."
Latest fitness feat: Kary, 44, will compete in a professional Toronto bodybuilding competition in May. "Many husbands would resent their wives looking amazing and strutting around onstage in a bikini (while) doing aerobics to crazy music," says Uche, who is helping Kary train for the event. "I'm very proud of the mother of my children, celebrating her energy, knowing that we are going to grow old together, healthy together."
John Ford and Jennifer Zorn-Ford
Known for: John is a founder of Swamp Donkey Adventure Racing. Jennifer, a respiratory therapist, also helps run the business.
Relationship status: Married for 20 years.
How fitness brought them together: Jennifer says John was much more dedicated to fitness when they first met. She quickly became just as passionate about it after friends introduced them to outdoor activities such as canoeing and portaging.
Their workout routine: The pair run together a few times a week. They also snowshoe, ski and adventure race. Their two kids often join them.
Why talking isn't important: John says it's hard to carry on a conversation during intense exercise such as running or skiing. But it's not about the words, he says. "Just doing something that's active and great for both of you is great for the relationship. It's about just spending time together."
Their most trying but rewarding sporting experience: John and Jennifer competed in an adventure race together for the first time last year -- a gruelling 24-hour event that "could either make or break" a relationship, says John, noting that the stress level was high. "You're racing for 24 hours straight. There's no sleep. You're eating while you're racing -- biking, paddling, running and navigating. You're making some important decisions and you're pushing yourselves and teammates out of your comfort level. It was an incredible experience."
Most sentimental fitness activity: For their 10th wedding anniversary, John and Jennifer canoed and portaged into their cabin, located on the Mantario Trail. "It's a place that is very near and dear to our hearts. We took both of our boys with us on that little adventure," says Jennifer.
Glen and Kelly Zelinsky
Sounds familiar from: A recent Free Press story that highlighted Kelly's 115-pound weight loss -- a mission the mother and daycare owner accomplished in a year.
Relationship status: Married since 2009.
When they started exercising together: Last year, when Kelly embarked on her weight-loss journey. That's when Kelly -- then a novice runner -- asked her husband to join her on her runs. The pair, along with Kelly's sister, would often run along the asphalt trail near their Transcona home. Glen says the pair haven't exercised together much since then, but he can't wait to get back on the trail with his wife this spring.
How physical fitness helped their relationship: "After long days, most people want to just flop down on the couch," says Glen, noting that exercising gives Kelly a newfound energy that has revived their lives.
On their first organized run: The pair ran a charity 5K last year, in which Kelly came in second in her age category and Glen came in first.
"I was taking some pictures when she was crossing the finish line. I would say it's brought us closer together."
Michael Horbay and Lisa Kappel
Relationship status: Together for four months.
How they met: Though friends in the local running community.
Best thing about sharing fitness with your partner: "When you're done a workout with someone and they're standing there waiting and they give you a high-five. It just consolidates things," says Kappel, a nurse who runs long distances. "It's just nice to have someone that understands what you're doing and appreciates it. And you both have that same feeling."
Their workout regimen: Horbay and Kappel attend running clinics at City Park Runners. They also spend many of their "dates" at the gym or running outdoors.
How exercise fuels their fire: Kappel says watching her boyfriend workout is an aphrodisiac. "It makes me feel like I'm on a high. I look at him and I'm more attracted to him."
Mutual goals: Horbay -- a Manitoba Liquor Mart customer service representative who has been running for 15 years -- says he feels a connection with Kappel because of their mutual respect of the other's goals. "We are each other's biggest cheerleaders."
How they avoid competing against each other: "We run together but we don't do the same kind of races," says Horbay, noting that he prefers to run shorter distances than Kappel, who prefers marathons.
Have an interesting story idea you'd like Shamona to write about? Contact her at email@example.com.