If you find yourself always tired, sick, injured, or depressed, you may be lacking in a few of these fitness fundamentals.

Here's the secret. All of your fitness goals require four things.

High Intensity Interval Training (HIIT), also called interval training, is the idea of doing a lot of work in a short amount of time.

No gym, minimal equipment, no training partners, little motivation. Here's what to do!

If weight loss is your goal, you shouldn't be running. It's time consuming, damaging on the joints, and may actually make you gain weight.

Distance for distance, walking burns the same amount of calories as running does.