Christie Brinkley continues to prove that age is nothing but a number.

On Monday, the 61-year-old model showed off her amazing body in an itty bitty two-piece on Instagram, Monday leaving us all wondering the same thing: How does she do it?

Christie Brinkley Talks Staying Sexy at 61

“I am wearing Neutrogens Wet Skin broad spectrum,” she wrote on the vacation post. “And I always have a hat!!”

The star has shared a number of adorable pics from her tropical getaway including one alongside her friends during a snorkeling trip.

“We saw 4 tortoises, sea fans in purple and yellow, puffer fish , Dory and Nemo fish, schools of colorful fish , and some huge barracudas...,” she captioned the adorable group snap. “One of whom chased Jack and me while snapping his Sharp jaw at us! Great undersea adventure!”

When it comes to Brinkley’s beauty routine, she has found it is easier to keep it simple.

"I tried Botox in the forehead. I'm not a fan. I won't ever do that again," Brinkley admitted to ET. "I didn't like the claustrophobic feeling of not being able to do whatever I want with my eyebrows."

"How you eat and how you exercise, these all play a tremendous role in how you feel, and therefore, how you look," Brinkley added. "And a smile will give your face an instant lift and it also releases endorphins."

WATCH: Christie Brinkley on Possibly Marrying John Mellencamp: 'I Don't Want to Jinx It!'

Another thing keeping a smile on her face is her boyfriend, John Mellencamp.

Watch the video below to learn more about the budding romance.