"You can't put a limit on anything. The more you dream, the farther you get. No matter what you set your imagination to, anything can happen." 

Michael Phelps
22 Olympic Medals (18 Gold)

What i think Michael is trying to tell us is that whatever you set your mind to, you can achieve and that anything is possible. The more you dream the more goals you have to achieve and the more hard work you'll put in. If you really set your mind to it anything can happen. Your actions and success is limitless and no one can stop you from achieving your dreams. Just like michael he worked really hard to achieve those 22 medals. He only achieved them because he set his mind to winning them and he dreamt of them and he knew that anything was possible.