Your diet might be perfect, but you need some muscle on your abs in order to see a six-pack. Here's how to build better abs!

Sara's once all-consuming fitness program left her running ragged and almost killed her enthusiasm for exercise. Learn how she revamped her routine and found a healthy medium.

Jaimie Alexander had to redefine and transform her body to play the war goddess Sif in ''Thor: The Dark World.'' Get the details in our exclusive video interview!

To get full access to Laura's insider tips on leaning out, check out her personal cutting regimen.

Body composition: there are a number of techniques available to measure it. Learn about all of them here.

What is the best HIIT workout? High Intensity Interval Training has become a popular way to burn more fat, improve endurance, and build strength.