Don't rely solely on weight machines because typically you can work more muscles and build greater practical strength with free weights…or even no weights.

The Fix:
To get the most benefit from each workout try to perform a mix of all kinds of exercises—ones using machines, body weight, free weights and dumbbells. Jay Dawes, instructor of kinesiology and health studies at the University of Central Oklahoma, suggests including two to three sets of a move like the lunge-and-press several times a week.

To do the lunge-and-press, hold a dumbbell in each hand at shoulder height with your arms bent close to sides and palms in. Keep your feet hip-width apart with one foot about a stride ahead of the other and your back heel lifted. With your abs contracted, bend your knees so the front knee aligns with your front ankle and the back knee points toward the ground. At the same time, straighten your arms to press the dumbbells overhead. Straighten your legs and lower the dumbbells to the starting position, and repeat for 12 to 15 repetitions.