4th and 5th Finger exercise
The fourth and fifth finger (a.k.a ring and pinky fingers) are the weakest fingers on your hand. Think about it. When you go to grab a glass of water or a door knob, you typically use your 1st three fingers to do most of the work. As a result, the 4th and 5th fingers generally lack strength and independence compared to the other fingers. However, they are very important to your piano playing. The following is an exercise I developed to strenghten my own fingers.
Amazingly,I've found that it produces instant results! You are only going to use your fourth and fifth fingers of the left and right hands. Remember to play with your fingers curved, keys touching your finger tips, and wrist slighly raised. If you feel your fingers "burning" from fatigue, Great! That's what you want. However if you feel "pain", stop immediately.