Credit: Fame Pictures, MAVRIXONLINE.COM

It's no secret that most stars work really freaking hard to maintain their sexy physiques. And recently, three trim and toned celebs stripped down to teeny-tiny two-pieces, which showed off the results of their grueling fitness routines and strict diets.

Blonde BFFs Julianne Hough and Ashley Tisdale soaked up sun in Miami on Sunday. The Rock of Ages actress, 23, wore a skimpy silver bikini and the High School Musical alum 26, opted for a printed halter style look. While in Florida together, Hough treated Tisdale to a screening of her upcoming flick Footloose.

"Saw a screening of #Footloose today. @juliannehough rocked it! Seriously everyone has to check it out, I can't stop dancing! :)" Tisdale wrote on Twitter.

She may have several years on these starlets (not to mention four children), but Heidi Klum's body is still in supermodel shape. The Project Runway star, 38, donned a black-and-white print string bikini while vacationing with her family on board a yacht off the coast of Ibiza, Spain on Monday.

"It's hot hot hot in Ibiza and my husband and I just ran into @ryanseacrest!!" she Tweeted to her fans.