luckily , as i am starting to write this part , i remember that in every one of his films , whenever rocky needs to become a better boxer , they show clips of him doing one-arm push-ups , running on the beach , punching slabs of meat , running the stairs of the art museum , gazing at adrian lovingly , or being yelled at by mickey or apollo creed or even paulie - all while his theme song plays , which is perhaps the greatest song in the world , `` gon na fly now . ''