Chances are, there are days when you wonder if you are up to the challenges life throws at you. Most go through times when they feel that the weight of the world is on their shoulders. Those are the days to reflect on the wisdom the people for whom it actually is--the global leaders, captains of industry, and great minds who face enormous challenges every day. They make decisions that affect people all over the world, including you and me, and it is a source of hope to see them approach this work with both seriousness and optimism.

Below are 20 quotes from great leaders and high achievers, to help inspire you when you feel burdened or just low on mental gas.

1. "When one has success, the answer is not to undo that success. It is to continue what has been done." - Chuck Schumer

2. "It's better to fight because if you don't fight, you can't win. Besides, even when you don't win, you can change the game." - Elizabeth Warren

3. "All it takes is one good person to restore hope." - Pope Francis

4. "Women speaking up for themselves and for those around them is the strongest force we have to change the world." - Melinda Gates

5. "Waging war is much more popular than negotiating, because there you need to compromise." - Juan Manuel Santos

6. "We watch our competitors, learn from them, see the things that they were doing for customers and copy those things as much as we can." - Jeff Bezos

7. "Listening to others, especially those with whom we disagree, tests our own ideas and beliefs. It forces us to recognize, with humility, that we don't have a monopoly on the truth." - Janet Yellen

8. "When we face uncertainty, we encourage everyone to press forward and believe in the values of the product." - Evan Spiegel

9. "You have to be able to accept failure to get better." - LeBron James

10. "I think sometimes in life the biggest challenges end up being the best things that happen in your life." - Tom Brady

11. "If you see something that is not right, not fair, not just, you have a moral obligation to do something about it." - John Lewis

12. "Put your consumers in focus, and listen to what they're actually saying, not what they tell you." - Daniel Ek

13. "Whoever saves a life - it is as if he has saved mankind entirely." - Raed Saleh

14. "I am a victim-oriented person. I like to see that the victims know that they have a voice." - Fatou Bensouda

15. "Trust is the most important aspect of being a journalist. If people don't trust or find you relatable - you will not have success." Gretchen Carlson

16. "It's my responsibility as attorney general to defend the rule of law, to uphold the Constitution on behalf of the people of this state. And that's what we're doing." - Bob Ferguson

17. "It's finding that balance between being true to a goal, but not being dogmatic." - Kirsten Green

18. "The ultimate aim is to use these general-purpose technologies and apply them to all sorts of important real world problems." - Demis Hassabis

19. "In tough times, everyone has to take their share of the pain." -Theresa May

20. "You have to believe in every aspect of the job and the organization and your ability to stay and do the job the right way, with your whole heart and your whole soul." -Theo Epstein