1. "It's lack of faith that makes people afraid of meeting challenges, and I believed in myself."
2. "If you even dream of beating me, you'd better wake up and apologize."
3. "Don't count the days, make the days count."
4. "He who is not courageous enough to take risks will accomplish nothing in life."
5. "I hated every minute of training, but I said, 'Don't quit. Suffer now and live the rest of your life as a champion.'"
6. "Bragging is when a person says something and can't do it. I do what I say."
7. "Impossible is just a big word thrown around by small men who find it easier to live in the world they've been given than to explore the power they have to change it. Impossible is not a fact — it's an opinion. Impossible is not a declaration — it's a dare. Impossible is potential. Impossible is temporary. Impossible is nothing."
8. "At home I am a nice guy: But I don't want the world to know. Humble people, I've found, don't get very far."
9. "A man who has no imagination has no wings."
10. "Float like a butterfly, sting like a bee. His hands can't hit what his eyes can't see. Now you see me, now you don't. George thinks he will, but I know he won't."
11. "Hating people because of their color is wrong. And it doesn't matter which color does the hating. It's just plain wrong."
12. "Service to others is the rent you pay for your room here on Earth."
13. "It isn't the mountains ahead to climb that wear you out; it's the pebble in your shoe."
14. "A man who views the world the same at 50 as he did at 20 has wasted 30 years of his life."
15. "I am the greatest, I said that even before I knew I was."
Read more: Legendary Boxer Muhammad Ali Dead at 74, NBC News Reports