CHRISTIE: STILL SMOKIN’ HOT AND FUN AT 61!

Christie brinkley 4

Supermodel Christie Brinkley has defied age, motherhood and four marriages to remain absolutely stunning and bikini-ready after turning 61 on Feb. 2!

“Everybody is blown away by how gorgeous she is,” gushed her 29-year-old daughter with former husband Billy Joel, Alexa Ray.

The infinitely youthful Christie is also mom to college freshman Jack Brinkley-Cook, 19, and lookalike daughter Sailor, 16, who’s also now modeling.

And she credited her amazing figure to a regular workout regimen.

“The more active I am, the better I feel,” said the former “Sports Illustrated” swimsuit edition cover girl.

Christie, who debuted on Broadway to rave reviews at the age of 56 in the long-running musical, “Chicago,” cranks out at least 100 push-ups a day, and sneaks in side leg-lifts and calf raises while she cooks and brushes her teeth. She also does yoga and is “hooked” on SoulCycle.

But she admitted to being human, confessing that her jeans size can fluctuate four inches if she gets lazy. But her solution is simple.

“I just get on the stick and exercise more!” she said.

Christie also maintains a healthy eating regimen, and was recently convinced by Sailor to make it even stricter when she converted from a vegetarian diet to one that’s nearly completely vegan.

“I treat every day like I’m eating to fuel my body,” said Christie, who starts her day with coffee and sheep’s milk yogurt with fruit, wheat germ and Anutra, a supplement that provides fiber and omega 3 antioxidants.

Meals typically feature beans and veggies.

“My snack is melon and walnuts,” Christie explained. “If I’m craving sweets, I’ll drink coconut water!”

She’s also devoted to her beauty rituals, which include her own line of Christie Brinkley Authentic Skincare products – which she says play a key role in her seemingly eternal youth.

“I go to my dermatologist about once a month and get special facials,” she added.

But her big tip for women of a certain vintage is to focus on the positive.

“I went through a tough decade in my 50s,” she said. “I lost my parents and went through a miserable divorce [from architect Peter Cook] while trying to be a pillar for my kids. But I made it through.

“Now I feel on top of my game!”