Where do they get their energy?

Jacob has gotten so crazy lately. He could just run back and forth across the room like 15-20 times. And our family room is really long! He's starting to have form when he runs, like a big kid. It's so weird. He used to just bounce but now he bends his legs more. I can't believe how much he's grown. He learns new things everyday. He knows almost all his letters and can identify them in a book, and knows a word that begins with them. He only has a few more letters to learn. We are working on learning to sing our ABC's. He can count to 3 now also. His vocabulary is huge that I can't even count how many words he says, and he speaks pretty clear these days also. He can say short simple sentences when he wants to. He also knows some sign language and we are probably getting him some sign language DVD's so we can all learn more. He's a smart kid ( at least that's what I think). He can finally jump too. For the longest time he would only get 1 leg off the ground, now he can get them both up! He can kick a football really far and get it in the air. And boy can he ever throw! He has got quite an arm. Everyday I wonder where he gets so much energy. We eat mostly the same things and yet he has twice as much energy than I do. I can't keep up with him sometimes. I love that kid. I really love him!