Here are some quotes about self-discipline:

- "I can’t always control my thoughts but I can choose how I respond to them." --David Cuschieri
- "With self-discipline most anything is possible." --Theodore Roosevelt
- "The first and best victory is to conquer self." -- Plato
- "You can never conquer the mountain. You can only conquer yourself." – Jim Whittaker
- "Self-discipline is doing what needs to be done when it needs to be done even when you don’t feel like doing it." Anonymous
- "By constant self-discipline and self-control you can develop greatness of character." Grenville Kleiser
- "Discipline is the bridge between goals and accomplishments."
- "The great master key to riches is nothing more or less than the self-discipline necessary to help you take full and complete possession of your own mind." – Napoleon Hill
- "We do today what they won’t, so tomorrow we can accomplish what they can’t." – Dwayne ‘The Rock’ Johnson
- "Through self-discipline comes freedom." – Aristotle
- "Discipline yourself and others won't need to." – John Wooden

I hope these quotes help you. Let me know if there's anything else I can help you with.