Personal experience refers to any event that made you think or feel a certain way about, or have a particular view of swimming, in this case. Someone who almost drowns at the age of eight, while playing around in a pool, will most likely not feel like getting back into that pool for fear that the same thing will happen again. Likewise, if a person has been around water her entire life, and all her family works at a pool or owns a pool, she might feel like just jumping right in when you're not ready. Even after going under and gulping some water she might still feel like jumping out of your arms and dashing for the side, just to jump back in again.
This little kid has not only had a good personal experience around water and pools, but she also seems to have a very powerful personal drive. Personal drive refers to how much we want to do something, and what we are willing to do to accomplish this goal. In children we see personal drive as an abundance of energy; if they get hurt, they cry for a second, then see something they like and jump back up to get it. In older kids we see this as mastering new skills like learning to play a favorite sport, learning how to draw and paint, learning how to play an instrument or even learning to ride a bike.
Let's go back to our two little swimmers. Susie is very energetic; in fact she's the "class clown" of her class. She has enough energy to light up New York City and couldn't sit still if promised a triple fudge sundae with her favorite sprinkles. Once she gets to the pool, she jumps right in, and bobs back to the side. While not exactly smart, Susie is showing a strong personal drive. She really wants to learn to swim so she does what the teacher tells her to do, and will even try new things with little to no resistance. On the other hand, Jimmy really doesn't like swim class that much. He likes being in the pool but he doesn't like lying on his back, going under water without goggles on, or jumping in unless the teacher is holding his hands. Jimmy just doesn't have that strong of a personal drive for swimming. He might love kicking the crap out of soccer ball after soccer ball, but the pool isn't a place he loves to be. This will slow down the rate that Jimmy learns to swim.
Personal experience and personal drive are very important factors in learning how to swim (as well as learning anything else), but the biggest factor for kids swimming and learning how to swim is learning capability.
American Red Cross Swimming and Water Safety Book
American Red Cross Fundamentals of Instructor Training Participants Manual