"Endurance is not a young person's game," said long-distance swimmer Diana Nyad, who, on her fifth attempt at age sixty-three, became the first person to swim from Cuba to Florida without a shark cage. "I thought I might even be better at sixty than I was at thirty. You have a body that's almost as strong, but you have a mind that's much stronger."

This is one of the lesser-appreciated reasons why swimming can be a lifelong, go-to sport. There's a mental game to the sport too, making swimming as much about our desire for a quiet mind—just as much as it attends to our desire for a lean, mean body.

And with time in the water, a lean, mean body you shall get. Here, five reasons why swimming is the best exercise for both body and mind.

It's a Total Body Workout

We weren't kidding about that "lean, mean" thing. Women's Health reported that swimming is nonpareil when it comes to burning calories, boosting metabolism, and firming every muscle in your body. When researchers at Indiana University compared recreational fitness swimmers with non-swimmers, they found that swimmers of all ages had more lean muscle and trimmer waists and hips—news that practically makes us want to go swimsuit shopping (and that's saying something).

So what's happening in the water that's so magical? Consider this: water is nearly 800 times denser than air, so your body has to work that much harder just to move forward.

While swimming is especially great for your core, hips, arms, shoulders, and glutes, this workout also manages to summon just about every muscle in your body. Even the little, neglected ones. Your body is working to stay balanced in the water at the same time your arms and legs and kick, push, and pull, so swimming helps develop the deep stabilizing muscles in the core and lower back that women often miss, Fitness reports.

A great workout and a great view? count us in!

It's an Intense Two-Fer...

In college you sought out two-for-one nights at the dive bar. Now, if you're looking for two-for-one workouts, swimming's got your number. One of the best-ever cardio workouts also functions as resistance training. Exercising in water offers 12 to 14 percent more resistance than exercising on land, the Bucknell University Athletic Department found. So in addition to burning calories as you swim, you build lean muscle, which fires up your metabolism so you can burn more calories even after you're back on dry land.

...That's Also Easy On Your Body

When your body enters the water, it becomes virtually weightless and joints say bye-bye to the effects of gravity. This makes swimming ideal for people with arthritis as well as those who are overweight or obese and may find load-bearing exercise too uncomfortable, research suggests, as well as the super-fit who simply want to exercise vigorously every morning.

"You can swim almost every day without risking injury," Joel Stager, Ph.D., director of the Counsilman Center for the Science of Swimming at Indiana University at Bloomington, told Women's Health. "You can't say the same for running or strength training."

Swimming can be more fun than slogging through another exercise class

It's Actually Fun

"People tend to enjoy swimming more than running or bike-riding," Hirofumi Tanaka, a professor of kinesiology and director of the Cardiovascular Aging Research Lab at the University of Texas, told TIME. And that means they stick with it; while about half of people who try a new exercise regimen give up within a few months, swimmers keep wading into the deep end.

It Keeps You Young and Happy

No, really. Research from Indiana University at Bloomington shows that swimmers are biologically up to 20 years younger than their actual age, with blood pressure and cholesterol levels, cardiovascular performance, central nervous system, and cognitive functioning all comparable to someone from another generation. If you're able to swim outside, the time in nature can help improve your mental and physical well-being by reducing stress and boosting your mood. Not to mention, water's symbolic power to heal and purify is as old as the earth itself. As Wallace J. Nichols, the author of Blue Mind: The Surprising Science That Shows How Being Near, In, On or Under Water Can Make You Happier, Healthier, More Connected and Better at What You Do, says, water "meditates you."

Meta-physical exercise—how's that for a two-fer?

"Something else happens when you dive into a world where clocks don't tick and inboxes don't ping," writes Julia Baird, who every morning meets a swim squad of women in hot pink swim caps just after sunrise on Australia's Manly Beach. "As your arms circle, swing and pull along the edge of a vast ocean, your mind wanders. And you experience awe."

And that never happens on the treadmill.