Resistance Bands

Available cheaply ($10-$20) at your local department or sporting goods store, a resistance band is an inexpensive way to expand your workout repertoire.

Fasten one end, or the middle, of the band securely, then stretch the band as much as you are able in any direction.

Examples:

Triceps Kickback
How To: Take a big step forward and place the middle of the band securely under you forward foot. Bend forward slightly at the waist and hold the handles of the band at your shoulders, arms bent at the elbows. Extend your arms back and behind you to full extension, then slowly return your hands to your shoulders.

Muscles: Triceps

Chest Press
How To: Wrap the band around your waist, bend your arms at the elbows, hands at your shoulders. Push your arms straight outward to full extension, then slowly return them to your shoulders.

Muscles: Biceps, pectorals