It's a constant battle to stay inspired and focused on the journey of life. I've found that great investors are one of the best sources for inspirational quotes as they have spent their lives accumulating wisdom to succeed over the long-term in the tuss-and-tumble of the markets. For those days when you need a boost, here are the best inspirational quotes from the greatest investors of all time.

1. "I will tell you how to become rich. Close the doors. Be fearful when others are greedy. Be greedy when others are fearful." -- Warren Buffett, Berkshire Hathaway

2. "The lesson of Buffett is, to succeed in a spectacular fashion you have to be spectacularly unusual." -- Michael Burry, Scion Asset Management

3. "It's not whether you're right or wrong that's important, but how much money you make when you're right and how much you lose when you're wrong." -- George Soros, Soros Fund Management

4. "The future is uncertain; it is always a difficult time to invest." -- John Griffin, Blue Ridge Capital

5. "A majority of life's errors are caused by forgetting what one is really trying to do." -- Charlie Munger, Berkshire Hathaway

6. "You adapt, evolve, compete or die." -- Paul Tudor Jones, Tudor Investment

7. "More than anything else, what differentiates people who live up to their potential from those who don't is a willingness to look at themselves and others objectively." -- Ray Dalio, Bridgewater Associates

8. "Be who you are and say what you feel, because those who mind don't matter, and those who matter don't mind." -- Bernard M. Baruch

9. "It is simple to see what is necessary, but not easy to be willing or able to do it." -- Howard Marks, Oaktree Capital

10. "An investment in knowledge pays the best interest." -- Benjamin Franklin

11. "If you want to have a better performance than the crowd, you must do things differently from the crowd." -- Sir John Templeton, Templeton Funds

12. "Opportunities come infrequently. When it rains gold, put out the bucket, not the thimble." -- Warren Buffett, Berkshire Hathaway

13. "If you don't have integrity, you have nothing. You can't buy it. You can have all the money in the world, but if you are not a moral and ethical person, you really have nothing." -- Henry Kravis, Kohlberg Kravis Roberts

14. "I'm only rich because I know when I'm wrong... I basically have survived by recognizing my mistakes." -- George Soros, Soros Fund Management

15. "Michael [Marcus] taught me one thing that was incredibly important... He taught me that you could make a million dollars. He showed me that if you applied yourself, great things could happen. It is very easy to miss the point that you really can do it." -- Bruce Kovner, Caxton Alternative Management

16. "If you don't keep getting better, you're going to do worse." -- Jim Simons, Renaissance Technologies

17. "Deserve what you want." -- Charlie Munger, Berkshire Hathaway

18. "Intellectual capital will always trump financial capital." -- Paul Tudor Jones, Tudor Investment

19. "One lucky break, or one supremely shrewd decision may account for more than a lifetime of journeyman efforts. But behind the luck or crucial decision there must usually exist a background of preparation and disciplined capacity." -- Benjamin Graham, Graham-Newman

20. "If a man didn't make mistakes, he'd own the world in a month. But if he didn't profit by his mistakes, he wouldn't own a blessed thing." -- Jesse Livermore

21. "Whatever task you undertake, do it with all your heart and soul. Always be courteous, never be discouraged. Beware of him who promises something for nothing. Do not blame anybody for your mistakes and failures. Do not look for approval except the consciousness of doing your best." -- Bernard M. Baruch

22. "Those who can not adjust to change will be swept aside by it. Those who recognize change and react accordingly will benefit." -- Jim Rogers, Rogers Holdings

23. "Your ultimate success or failure will depend on your ability to ignore the worries of the world long enough to allow your investments to succeed." -- Peter Lynch, Fidelity Investments

24. "Warren Buffett has become one hell of a lot better investor since the day I met him, and so have I. If we had been frozen at any given stage, with the knowledge we had, the record would have been much worse than it is. So the game is to keep learning, and I don't think people are going to keep learning who don't like the learning process." -- Charlie Munger, Berkshire Hathaway

25. "You only have to do a very few things right in your life so long as you don't do too many things wrong." -- Warren Buffett

Foolish takeaway

Life is a journey, not a sprint. For over 20 years, The Motley Fool has worked to inspire people to success on the path to financial freedom. While there will be ups-and-downs, continuously learning, thinking for yourself, developing good habits, focusing on the long term, and having fun on the journey is what you need to set yourself up for success in life. Sometimes we all need inspirational quotes from those who have come before us to remind ourselves of that.