Blame Jane Fonda. She was the one who started it, appearing stunningly youthful at Oscar ceremonies in the 1980s, even though she was well into what most people would call middle age.

Then came her book, Women Coming of Age, and the Jane Fonda workout tapes and “go for the burn” and, before we knew it, 40 was the new 30. And now here we all are, tempted to spend thousands of dollars a year on makeup and firming creams, Botox and personal trainers.

These days, the Hollywood standard for women turning 40 is to remain fresh and glowing, even if they can’t ignore the mental adjustment of entering what is — literally, statistically — middle age.

“I don’t want to,” Jennifer Aniston, who turned 40 on Feb. 11, told talk-show host Ellen DeGeneres.

“I found a really long grey hair and it kind of flipped me out.”

In April, Jennifer Lopez told People magazine that she had forbidden her husband, Marc Anthony, to talk about the fact that she was turning 40 in June.

Rachel Hunter told Woman’s Day that turning 40 this year doesn’t bother her, but that was before her 27-year-old fiancé, Jarret Stoll, a Saskatchewan native who plays centre for the Los Angeles Kings, jilted her weeks before their August wedding.

“I’m doing sit-ups every day so that I could maybe look like Helen Mirren in a bikini,” Renée Zellweger, 40, told Marie Claire in January, referring to a picture of Mirren at 63 sporting a bikini and a curvy, smooth, toned body that gave hope to women around the world.

“It’s a pretty strong group,” says David Clemmer, founder of Judy Inc., a management company representing fashion stylists, hair and makeup artists and set designers.

Some of his recent clients include Catherine Zeta-Jones and Cate Blanchett, both 40 this year.

Being subtle works best for women as they age, says Clemmer, who is also the wardrobe consultant for the makeover series Style By Jury, which airs on the W Network.

Some women make the mistake of trying to cling to their curves by buying clothes that are too small or too revealing or they overdo it with accessories.

“I think age is a great thing,” says Clemmer. “Now, talk to me again in 20 years.”