They’re expensive and messy and they hog the bed. Yet if you’re among the millions of pet owners across the country, you just can’t imagine life without your beloved dog, cat or other animal companion.

Why are we so hell-bent on making these critters part of the family? Probably because of the incredible health and happiness benefits they offer —something researchers are only recently beginning to take a closer look at, says Marty Becker, DVM, the featured veterinarian at and veterinary contributor for Good Morning America. “The more time you spend with your four-legged companion, the better you feel,” explains Dr. Becker.

Check out these seven science-backed ways pets boost the bliss in our lives. You’ll feel so appreciative you’ll never lose your cool over a spilled water dish again!

1. They make us more active.

Whether you’re tossing a tennis ball at the dog park or dancing around the living room with your cat, you’re moving around — and that means burning calories, getting your heart rate up and scoring the big mood and energy boosts provided by quick bursts of exercise. Even if all you do is walk your pooch down the sidewalk and back twice a day, that exercise adds up over time. “Dog owners walk 79 percent further each day than people who don’t have a dog,” says David Niven, Ph.D., a psychologist and social scientist at Ohio State University and the author of 100 Simple Secrets Why Dogs Make Us Happy. It’s not as intense as spin class, sure, but you’re working off more calories than you would if you’d sacked out on the couch.

"Biggie is my 3-year-old pitbull mix. He was living the single life until I heard about a puppy who seemed to be treated poorly," Carolyne Villanueva tells us. "I decided to take the pup in and name her Ziggy. She is now almost 6 months and the two are inseparable. Our summer has consisted of beach trips, hiking adventures, days at home playing in their kiddie pool, puppy training and visits to the dog park."

2. They keep us healthy.

The American Heart Association confirms it: Pet ownership is linked to a reduction in cardiovascular disease risk factors, such as lower blood pressure, lower cholesterol levels and a lower likelihood of obesity. Another study found that cat owners were 40 percent less likely than their feline-free counterparts to have a heart attack or stroke, says Dr. Becker. Beyond the exercise factor, experts aren’t entirely sure why pets improve our health, but they certainly do. “Think of your dog or cat as free medicine you already have in your home that can help you maintain optimum health,” adds Dr. Becker.

"This is our chocolate lab, Whisky, giving her sister some sugar", says Jay Moye.

3. They help us develop empathy.

Some research suggests that kids who have pets become more nurturing, giving adults — perhaps because they learn from a young age that all living creatures need comfort and feel pain. But even people who bring home their first pet as an adult tend to develop a stronger sense of empathy, thanks to their furry or feathered buddy. “Taking care of an animal reminds you that all humans and animals have needs that may eclipse your own, and you’re able to see things from others’ point of view. That helps you become more caring and compassionate,” says Niven.

"I can't resist a bedtime #selfie with Sasha", says Dominic Humphry-Arewa.

4. They give us a self-esteem kick.

Maybe it’s because they make us feel needed — after all, someone has to fill up that food bowl and stop by the dog run every morning! Or perhaps it has to do with the unconditional love they shower us with, or the fact that they’re completely nonjudgmental about our lifestyles. Whatever the reason, a 2011 study published in the Journal of Personality and Social Psychology found that pet owners reported higher levels of self-esteem as well as a greater sense of belonging and a more meaningful existence than non-pet owners.

5. They increase our social connections.

Ever notice that when you’re out with your pet, strangers are more apt to smile, say hello, even strike up a conversation? And when you share a goofy video clip or retell a funny story about Fluffy or Fido, people immediately chime in and share their own pet’s similarly silly antics. Those brief exchanges seem meaningless, but they actually leave us feeling less isolated and more in sync with our community, says Niven. And that makes us happier because people are hard-wired to feel good when they feel connected to others.

Animals are conversation starters and icebreakers, so it’s no surprise that pet parent dating websites, pet/human fitness classes and other social gatherings for pet owners are becoming more popular. “People who have pets are perceived by others to be more social and open,” says Niven. “That can make your social circle wider and more diverse, resulting in less loneliness.”

Isabella Callaza submits: "Summer in France is great for Napo: a time for running outside, meeting with his girlfriend and enjoying the sunshine!"

6. Petting them brightens our mood.

Sure, it’s soothing for pets to be stroked and touched by us, but we get a huge physiological payback too: Just a few minutes of petting a pooch signals our brain to crank up production of the hormones serotonin and oxytocin — two calming chemicals that make us feel more relaxed and at peace, according to research from the University of Missouri-Columbia. And running your hand against your dog’s fur also decreases levels of the stress hormone cortisol. The study only involved canines, but Niven suspects the same serenity boost can occur when you pet, nuzzle or rub any animal companion.

7. They bring order to our lives.

Going for daily walks, establishing playtime and eating routines and making regular vet appointments — yeah, it can all start to feel like drudge work after a while. But there’s an upside to responsible pet parent behavior: It helps bring routine and discipline to our day, and that benefits us as much as it does them, asserts Niven. “These mundane tasks become habits to bring structure to the day, and when we feel like there is order and purpose to our lives, we tend to feel happier and be more productive.”