Push ups are one of the best exercises around. The reason push ups are one of the best exercise is the countless variations available of the exercise. One such variation of the classic push up is the soccer ball push up. Some people with advocate using a medicine ball, but I think more people have a soccer ball lying around the house than a medicine ball. Either way, use a ball (even a basketball) you have around the house. Place both hands on the ball and keep your feet together. Perform push ups just like you would in the classic mode. You will notice that your core must really engage to keep your balance. This works a good portion of your body with just one exercise.
You can also vary the difficulty of the exercise by how wide apart you position your feet. Feet wide apart creates a more stable base, thus making the exercise easier. Feet close together destabilizes your base and more muscles engage to keep your balance. Once you have mastered feet close together, raise one foot off the ground to make it even more difficult.
You could even switch how you position your hands. Start out with thumbs facing in, with fingers forward. You could also try thumbs facing back and fingers facing in. Theses variations will target your chest and shoulders differently.
Another variation is having one hand on the ground and the other on the ball. Perform two repetitions and then switch hands being on the floor. Combine these various positions to come up with many different combinations. Use your imagination and come up with some new variations of your own. Soon you will come up with your own soccer ball push up workout. I hope this helps you reach your fitness goals!