Gearing up for beach bikini season, Amanda Bynes headed over to a Thousand Oaks fitness center on Wednesday (May 28) for an intense workout.

The “All That” actress spent a few hours at Cardio Barre before emerging with a smile on her face for a job well done.

Apparently Amanda is an avid supporter of the gym as she’s even written a testimonial that appears on their official website.

Bynes gushes, "I have been coming to Cardio Barre for 6 years. It is an amazing workout that tones, tightens, and is so fun at the same time! I am a huge fan!"

Other big name celebrities who frequent Cardio Barre include Ashlee Simpson, Jenna Elfman, Megan Hilty, Dakota Fanning and Melissa Joan Hart.