The stability ball has become an integral part of many "fusion" fitness programs, providing a link between different kinds of exercise, such as muscle conditioning, Pilates, and even some forms of yoga. The reason? The ball lets you combine strength, flexibility, and balance training -- three basic elements of fitness.

In addition to its versatility, the ball is very forgiving, making it ideal for beginners. By using the ball to modify a difficult exercise, such as the push-up, you can achieve correct form without straining. Yet you can also use it to challenge yourself.

Each of the exercises below build strength, flexibility, and balance. Begin with the strength training, then move to the flexibility exercise to help stretch and release the muscles you just used. Finally, the balance portion helps you recenter the body and be aware of your breath.

You can choose to do one routine a day, or power through all three routines in one session for a more invigorating workout. Ideally, aim for three to five times per week. "As you improve flexibility, you use your muscles differently and more efficiently, giving your body a longer, more elegant look."

Exercise 1: Crunch > Arch > Seated Twist
Exercise 2: Scissor > Plow Stretch > Boat Pose
Exercise 3: Pushup > Chest Stretch > Tree Pose

Expert and model: Ellen Barrett, creator of best-selling fitness DVD "Burn and Firm Pilates" and author of "SexyYoga."