Being active only during workouts -- Most of us live sedentary lives. Workouts become harder to stick with when they're the only time you're physically active. Sitting around slows circulation and fat burning, counteracting your workouts. Do more outside the gym. Park the car and walk more. Play sports. Add hobbies and get out more. Or stay in, clean up the yard or remodel a room. It's true what they say about bodies in motion -- they tend to stay in motion, and that's a good thing.

Also check out... Revealed! WORST Leg Exercises Worst Abdominal Exercises Least Effective Exercises for Your Butt Best Butt Exercises

Failing to fuel your body with a sound diet -- Nutrients key the regeneration of muscles. Your body needs protein and vitamins... not excess fat and junk food. Make sure what you take in each meal furthers your fitness goals, rather than hamper them. Go with lean meat, fruits and vegetables over processed and fatty foods. Make sure you eat regularly to keep your metabolism moving and to maintain energy for those workouts. Plan your diet like you plan your workouts if possible. It matters just as much.