First baseman Ryan Zimmerman: “I know I have to make changes. But it’s hard. You learn to play one way — all out, every day — your whole life. And you’re proud of it.” (John McDonnell/The Washington Post)

Take a couple of days off. Don’t work so hard. Knock off early.

Those are words that many of us, dedicated to work and defined by it, too, dread to hear. That includes most pro athletes. From childhood, they’ve looked in the mirror and asked, “Is anybody outhustling me?” Play with pain? Of course.

But in baseball, a time comes to maximize what’s left to give. That trimming of sail, in the name of wisdom, can feel tougher than hard work.

Luckily, baseball can be played, and for some should be played, with a constructive laziness. Witness the Nationals. Their greatest danger this season is that three-quarters of the heart of their order — Ryan Zimmerman, Jayson Werth and Anthony Rendon — can’t seem to remain intact in a sport that, on most days and most plays, just doesn’t have to be all that tough.

In 2014, when the Nats won 96 games, those three missed a combined 125 games, which is a lot. In 2015, they missed 223 games, which is crippling. If that’s a trend, the Nats can forget the 2016 playoffs. Job one: Figure out how to keep this trio on the field as much as possible — while also not playing them too much.

Manager Dusty Baker claims that preservation of veterans, and spotting exhaustion in the young, such as Rendon, is one of his specialties. “I can see a player’s gait change before they pull a hamstring [and miss a month],” he says.

Sometimes, playing less leads to playing more; those days off can be preventive medicine. And playing under control, with less apparent passion, can be what’s best for the club. With Bryce Harper and durable Daniel Murphy, the Nats have the makings of a potent lineup core. But will Zimmerman, Werth and Rendon do what’s necessary — and in different ways they will all hate it — to put the team first? And will Baker enforce it?

In recent years, swagger, diving for balls (even if you break your wrist) or sliding into home headfirst (even if your forehead hits the ground first) has been a Nats badge of honor. But for these three key hitters, it’s time for some adaptive evolution before the Nats’ chances over the next three years with Harper on board become extinct.

If that means the equivalent of a voluntary “month off” — spaced over six months — for Zimmerman and Werth, so be it. If Jayson doesn’t like it, he can go kick a garden gnome. No, on second thought, don’t kick anything.

If it means Baker must watch Rendon’s gait or bat speed for the first signs that he’s tiring — when players are more likely to get hurt — and give him a day or two off, while he wails, just do it.

Will such preventive medicine work? Is worrywart really a good answer? Maybe not. This trio may end up hobbled again. But all three have clear career patterns. It’s time to face facts about them.

It doesn’t matter that Zimmerman was almost indestructible when young or that Werth played 147 games in 2014 at age 35. That’s not where they are now. Just as they adjust to what pitchers throw, now they must adapt to their bodies.

Werth’s days as a leader by hell-bent example are more likely to damage him, and his team, from now on. The next time you see him round first base hard, then slide to a stop, don’t cheer. Don’t encourage him.

Tell him: Be like Hank Aaron from age 37 to 40. Plan days off before you get exhausted by the grind. Skip a tough right-hander. Bat less often, but produce at your career-best levels when you do play. It’s rare at that age. But if Werth wants tips, ask Baker, who batted behind Aaron back then.

Aaron, who rarely missed a game his first 17 years, started taking about a month “off” every summer — missing an average of 33 games and cutting his annual plate appearances by 173. What happened? Aaron went from 36 homers a year from 1955 to 1970 to 35 homers a year from 1971 to 1974! Werth hit .221 last year. If he doesn’t think he needs 30-plus days off, he’s nuts.

Zimmerman has aged at a normal pace, hitting the wall around age 30. That’s when chronic injuries bite instead of bark, send you to the bench for a month not just to the rubbing table. Zimmerman’s left foot (plantar fasciitis) will have to be monitored and babied every day for the rest of his career. Or he won’t have much career left.

For 11 years, Zimmerman has sacrificed his body to the service of the king — first his throwing shoulder, which is shot, and now that heel. It’s honorable. But it’s got to stop. If he cares about his teammates, and the millions he’s being paid, he’ll spend this season working on a scary attitude adjustment: Cut back on acrobatic athletic plays or running the bases aggressively. Don’t do everything you can; just do what you should. That transition is genuinely hard. Some never make it. And their rapid tailspin past age 30 is often the result.

“I know I have to make changes,” he told me. “But it’s hard. You learn to play one way — all out, every day — your whole life. And you’re proud of it.”

In the offseason, he worked with an AlterG treadmill so there’d be much less weight landing on his foot when he ran. Right now, he’s not playing an exhibition game for about two more weeks. He’s not hurt. But he’s only got so many plants and pivots in that foot. Don’t waste ’em in Viera.

Unfortunately, there are also players who must learn how to survive a tendency toward injury when they are only 25 — a rare misfortune. For the Nats, that player may be Rendon, who, including college, has only had two injury-free years in the past seven.

Early miseries aren’t always a career disaster. Paul Molitor was even more injury-prone than Rendon at the same age. A shift from second base to third helped somewhat, a transition Rendon is now making. Past 30, the designated hitter helped Molitor. But mostly he just learned his risk tolerance and, over time, visited the DL less. And had 3,319 hits.

Many great players never gear back, bless ’em. But plenty do, and there’s no shame. From 20 through 30, Ted Williams missed six games a year. From age 35 to 41, he played 30 fewer games a season than that — yes, that extra “month off.” Results? He had a seven-year OPS of 1.102, only a hair below his level in his 20s.

Are these suggestions a partial solution for the Nats? Will the team’s new medical staff have fresh ideas? Or is there any fix for men who’ve missed 89 (Werth), 91 (Rendon) and 168 games (Zimmerman) the past two years?

If there’s a cure, or even a palliative for this trio, it better be found. Because injuries, and lost games, at this pace are fatal almost every time.

For more by Thomas Boswell, visit washingtonpost.com/boswell.