BOSTON — Bill Parcells is a card-carrying member of an exclusive club. Only 13 NFL head coaches held membership, but Parcells welcomed one more to the group on Sunday.

The Patriots’ Bill Belichick turned 65 and became the 14th man to be an NFL head coach at or past his 65th birthday.

Seattle’s Pete Carroll is the only other active coach on the list, though Arizona’s Bruce Arians will join in October.

Naturally, Parcells isn’t surprised that Belichick, his defensive coordintor for the Giants, Patriots and Jets, lasted this long. Both men share a passion and love for the game, but as Parcells pointed out when we spoke on Wednesday, the job isn’t always easy.

Sure, it might look like a piece of cake on the outside when you have a dominating personality like Parcells or a no-nonsense approach like Belichick, but the workload, demands and stress can take their toll.

“Hey listen, when you enjoy what you’re doing … and, you know, Bill loves football, all of us that were in it for that long, you really have to like it,” Parcells said. “It’s more fun than it is work. But, there are times when it can get tedious, like any other job.”

As the years have passed, the job of an NFL head coach has gotten more demanding, and more exhausting. Parcells, a head coach for 19 seasons, spoke about those demands and how much harder it is nowadays, which makes Belichick’s longevity, success and desire to continue more noteworthy accomplishments.

“They go right from the playoffs, or in this case, the Super Bowl, and they’re right into free agency. There’s no time frame to relax. There’s always something you have to attend to,” Parcells said. “Whereas (in the past), when the season ended a little early, and the playoffs and Super Bowl ended in January, or the playoffs were over and you didn’t go to the Super Bowl, before free agency, you had a two- or three-month period before the draft where you could kind of recharge. You could do your scouting, but it was a lot less urgent. You had more time to do it.

“Now, with free agency, the combine, draft, rookie camp, OTAs (organized team activities), you really don’t get a break until the summer. And once you start back in, it’s literally 24/7 for the entire season. It’s seven days a week. There aren’t any days off. There’s no time to really relax.”

George Halas, the legendary Bears coach, was 72 when he retired. He was a head coach for 40 years. Miami’s Don Shula, who retired at 65, had 33 years on the books, while Paul Brown retired at 67 after 25 years.

Belichick was head coach of the Browns for five years and is heading into his 18th season at the helm of the Patriots. During this year’s Super Bowl victory celebration parade and rally at City Hall Plaza, he told the crowd there was only one way to get championship No. 6: “No days off.”

Parcells knows the drill. He said he wasn’t a sleep-at-the-office kind of guy, although he admits to staying on the couch on occasion. But he certainly understands how the hours pile up trying to produce a championship product.

“Like any industry or any job, there are times when it can become a little tiresome,” Parcells said.

“For me, the times would be like if you had a late 4 o’clock game, or a Monday night game, and you were out of town, and then you had to fly back, and you’re flying through the night, or into the early morning in some cases, West Coast to East Coast. Then ride the bus back to the stadium, and then go right to work. Those were the times I noticed. That would beat me up for a day or two until I got a good night’s sleep.”

Belichick doesn’t appear to have any signs of wear and tear, or concessions to age. There haven’t been any noticeable alterations or changes in his workload. Of late, he’s been all across the country, back and forth to pro days, with no let up scouting prospects for the upcoming draft.

As for how much longer Belichick will continue, last week he told Suzy Welch on CNBC that he was “good for a while.”

Parcells, for what it’s worth, isn’t in the speculation business.

“I don’t have a crystal ball,” he said, “but as long as he’s happy and healthy and enjoying it, I’m sure he’ll keep doing it.”