Mets pitching coach Phil Regan believes pitching is about perspiration and inspiration.

Perspiration comes in the form of hard work and the Mets pitching staff is a hard-working group, led by Jacob deGrom.

Inspiration is added in different ways by Regan, who at 82 has more experience than any other pitching coach out there.

On the Mets bulletin board every day Regan writes a little note, something to think about.

Some may scoff at such a thing for major leaguers, but if you look at it from today’s perspective, think of it as text to success.

These come in hard times and good times.

After that painful loss to the Braves last week, when Steven Matz was pulled after retiring 14 straight and the usually reliable Seth Lugo had the worst relief outing of his career, The Post noticed Regan saunter through the visiting clubhouse the next afternoon at SunTrust Park and scribble just such a message.

Here were Regan’s words: “You learn more from failure than success! Don’t let it stop you!’’

Let’s call it Phil-osophy.

Before Sunday’s 11-5 win over the Royals, a game the Mets had to win, setting up the huge homestand that begins Tuesday at Citi Field against the Indians, Regan wrote: “Never let it rest until your good is better and your better is best.’’

Nothing too heavy but something to think about, and not just for pitchers, for all players, and even curious media.

“I’ve just picked ’em up through the years,’’ Regan told The Post.

The Mets’ pitching has improved since the All-Star break. Some of that could be due to the weaker competition and some could be a result of a talented rotation coming together and a tattered bullpen making improvements.

Whatever the reason, since the All-Star break the Mets have posted a 3.23 ERA, the second best mark in the majors behind the Indians, who own a 3.15 mark.

At 82, Regan relates to 20-somethings. It’s interesting to note the Phillies have tried to fix their hitting woes by turning to Charlie Manuel, who at 75, remains a hitting guru.

Perhaps baseball is smartening up and finding a place for seniors other than senior adviser.

Regan leans on his experience with legends like former Dodgers teammate Sandy Koufax. He takes their words and puts it in today’s world.

“That’s what I try to tell the kids in the minor leagues, you have to know how you get a hitter out,’’ Regan said “Not how [Noah] Syndergaard gets someone out, throwing 100 miles per hour or [Edwin] Diaz at 98. You throw 92-93, how do you get them out?’’

When Regan was asked the biggest thing he has learned since replacing Dave Eiland (and he made it clear that he was an Eiland fan), he offered an intriguing answer.

“More patience,’’ Regan said. “I’m a patient man but I have to have more patience, because the focus is so high. For instance Diaz, there is a lot of pressure on him right now, but we still have to have the patience that when he comes out every day to work and say, ‘Hey, the results are coming.’ And they are. We have to have that patience. We don’t want to wait all year, but I do think we are getting close to it.’’

Diaz had his best slider Sunday and told The Post, “I’m making good progress with Phil.’’

“He’s a great kid and he works hard,’’ Regan said. “I’ve said to him, even with the bases loaded and the count goes to 3-2, you still make your pitch because it’s better to give up one run than four. Just because it’s 3-2, don’t throw the ball down the middle.”

Diaz nearly gave up such a grand slam Friday night, but the Ryan O’Hearn home run was reviewed and the blast was ruled foul. On Sunday, Diaz was much better.

Phil-osophy is not just limited to pitchers.

“One day after we hit a home run to win the game I put up: ‘Yesterday’s home run won’t win today’s game,’ ” Regan said with a chuckle.

“Or when it was real hot I put up: ‘No player ever drowned in his own sweat.’ ”

Then there is this dandy about results: “A mosquito never got a pat on the back until he started to work.’’

Keep ’em coming, Phil.