Hayden Panettiere is a dedicated “gym rat”.  This 18-year-old Heroes star hits the gym 7 times a week with her L.A. trainer Jonathan Baron.  Apparently, this 5-foot-1 actress has a natural tendency to bulk up, so she goes easy on the weights and heavy on the reps. Hayden explained:

“For me, it’s very easy to build muscle, so it’s about being lean and doing repetitive exercises.” -    Us Magazine

Hayden wasn’t always this disciplned, but now that she’s “growing into her adult body”, she is feeling the pressure to be more dilligent about working out.

“I’m more disciplined about going to the gym and keeping it up. In the past, I’d go then stop.” -    Us Magazine

I’m impressed with this young celeb’s new found commitment to fitness.  Keep up the hard work Hayden, because it is clearly paying off.  Hayden Panettiere looks like a toned and healthy FitCeleb!