Kenny Chesney's songs may be about whiling away his days in sun-baked margaritavilles, but his own summers are frenetic. That's because in 2016, the list of male pop stars who can routinely sell out stadiums pretty much begins and ends with him. Last summer he played to 55,000 at the Rose Bowl (in its first-ever country show), 58,000 at MetLife Stadium, and 54,000 at Mile High Stadium; he sold out his twelfth and thirteenth nights at Gillette Stadium and broke his own records at Heinz Field, Lambeau Field, Lincoln Financial Field in Philly, and Arrowhead Stadium in Kansas City. And these aren't ballad-heavy evenings; they're two-plus hours of relentlessly carbonated pop-country, punctuated by sprinting and jumping and hat-flipping.

Chesney may sing about boats, beaches, and Barbados, but his health ethic is dead serious—especially for a guy who grew up in Tennessee, a place not particularly noted for its judicious approach to portion sizes. Today he's 47, and it's still paying dividends.

Read MoreThe 6 Worst Workouts at the Gym

You should stop doing crunches right about now

By Bill Bradley

"I felt better on stage than I've ever felt this past summer," he tells us. "I wasn't feeding my body negative things. I wasn't killing myself in the gym, but working real hard when there. When I was 27, I didn't have to make those decisions. Now I do." The main decision? "If anything takes away from me being able to do that, it's not in my life anymore."

Here are some of the decisions that've enabled him to play stadiums on Saturday nights for 15 years running. (This year's tour starts March 19.)

"THE BEST I'VE EVER FELT"

Two things contributed to Chesney's feeling better than ever last year:

1. A fancy new treadmill: He started using a Woodway treadmill called the Curve, a machine that's 100 percent Chesney-powered. "There's no plugging it in. Your body does the work and moves the belt. Walking on it is hard, much less sprinting. Running on the Curve got me in better shape than I've ever been in."

2. Not drinking beer: No, really. "I didn't drink out on the road, which might surprise some people." And it wasn't as hard as fans might think. "Once I make up my mind to do something, that's what I'm gonna do. I have that mental makeup. I can go down and hang out on the boat in the island and stay for an overextended vacation, enjoy it, then come home and cut it off."

Allister AnnMAKE YOUR OWN CALENDAR

For the past 15 years, Chesney's put himself on an annual cycle. Workout season begins as the year does. "After New Year's, I put it on lockdown. I train hard starting the first week of January. I'm pretty tunnel-vision: I know what it takes to do what my body wants when I get up on stage." Tour prep continues through February until go time in March. "Last year we worked every Wednesday, Thursday, and Saturday from the end of March to the end of August, without a weekend off," he says. After the tour winds down in the fall, Chesney decamps to the Caribbean. "I give myself a break for two or three months to do whatever I want. My body needs it. And after the first of the year, I put it on lockdown again."

SET A WEEKLY ROUTINE (AND KEEP IT)

For his 2015 tour, Chesney went for the heart. Fighting some lingering shoulder issues, he and his Nashville-based trainer, Daniel Meng, steered away from heavy weights in favor of reps and cardio. "I don't work out any more than an hour," Chesney says. "But that hour is intense. There's not a lot of bullshit going on; we get it done and get out. I'm not the kind of person who stays in there for two hours a day—I got too much to do." The work paid off: Last year Chesney got leaner than ever before.

Monday, Tuesday, Wednesday: Three days of intense morning workouts. "I wasn't lifting heavy to try to gain size," he says. "I was trying to lean down and gain flexibility." On Wednesday afternoon, he flies out to wherever his show is, leading to…

Thursday: The hard cardio day, including the Curve. "We worked at keeping my heart rate up. When I left the gym, I was still burning calories."

Friday: Thanks to setup and soundcheck, Friday counts as a day off. But he still finds time to hit a local gym, and (usually) not get noticed. "I'll do that by myself—I can walk between the raindrops pretty good. But if we're in a small market and there's only one gym, that can be tougher."

Saturday: Light cardio in the morning, and then the 150-minute sprint of a show. Chesney has yet to track the number of calories he burns every performance—"There's gotta be a way to measure it with all these gadgets we have now, but I've never done it," he says—but aside from flying to the stage on a chair suspended over the audience, he doesn't stop moving.

Sunday: The flight home, and rewards in the form of a cheat meal when he gets there. (More on that below.)

Read MoreMeet Three Country Badasses Who Are Shaking Up the Nashville EstablishmentBy Will Welch

KENNY CHESNEY'S** **SHOW-DAY DIET

"I load up on carbs early. I don't eat any after 5:00, whether on or off the road." The key, he says, is developing a pattern, but he admits to it not being an easy pattern. "I'm an emotional eater. We all are. I was brought up not eating this way. And when you have that kind of focus on your diet, there's no social life (laughs). Your friends, your girlfriend, everybody wants to go out and have drinks. But when you're on this kind of specific diet, you look kind of weird when you go to a restaurant and bring your dinner with you, because it has to be measured." No, seriously, he did that once. "Even if you order something really healthy, nine times out of ten it's full of salt, and stuff you would not make at your house. And I don't want to ask the waiter if everything's made of coconut oil. That's weird."

Breakfast: Five scrambled egg whites in coconut oil (plus one real egg, for the fat) with jalapeños, tomatoes, sweet peppers, and cilantro. He'll also have a fist-sized portion of fruit. After his morning workout, he'll down a Quest Bar.

Lunch: Salmon or chicken, steamed vegetables, small portion of brown rice.

Dinner: Salmon or chicken (whichever wasn't for lunch), extra portion of vegetables, cucumbers and tomatoes.

Snacks: "If I get hungry, I'll eat some raw almonds now and then. It's fat, but it's good fat."

After the show: "Instead of eating pizza and drinking beer, like I used to do 15 years ago, I'll mix two scoops of chocolate protein powder in water—not a protein shake with a lot of carbs, just pure protein. When I'm in the zone, that's my fourth meal of the day."

Sunday night's cheat meal: When Chesney gets back home after a show, he'll dig into Italian or Mexican. "It helps you mentally. You have to allow yourself time to get away. I do anyway. I grew up in an area where everything revolves around food." Even his cheat meals still don't have bread, but the payoff comes on show night: "Once you feel that kind of love coming at you, it makes not eating bread worth it."

Most Popular

GQ RecommendsThe Alex Mill Sale Just Went Double PlatinumBy Gerald Ortiz

GQ RecommendsThe Best Hair Gel for Men Is Spiking Our InterestBy Adrian Clark

GQ RecommendsThe Raddest Winter Jacket Is The One You Can't SeeBy Charles McFarlane