- 21 Irrefutable Laws of Leadership by John C. Maxwell - We are all Leaders in our lives and taking in these 21 Irrefutable Laws is a great way to start leading your life in the best way possible.
- The Power of Now by Eckhart Tolle - Learn to stop thinking and start living. Enjoy the moment, work in the moment towards your future, let go of worries, anxieties and take some of the best advice ever written.
- The New Psychocybernetics by Dr. Maxwell Maltz and Dan Kennedy - Changing how you view yourself is a key part in self-improvement. Instead of growing to the point where you cannot help but view yourself in a positive light why don’t you do the easier thing and change how you view yourself first and then let your actions flow accordingly.
- Learned Optimism by Martin P. Seligman - Depression and Anxiety disorders are incredibly prominent and widely spread, especially in today's society. Learn to go against this by becoming more optimistic, leading a happier life and becoming more resilient to all the negativity of the world!
- The Way of the Superior Man by David Deida - What are the real interactions in relationships? How do you hold an amazing relationship and how do you best interact with your partner? Become a superior man than you were before!
- Cultivate an Unshakable Character by Jim Rohn - There are only a few things you need to cultivate an unshakable character, but these things are crucially important. Learn to develop:
- Personal Responsibility
- Good Health
- The Last Lecture by Randy Pausch - This book describes the speech Randy Pausch gave in 2007. It was to be his last speech. He touched on topics such as: What matters to you? What matters in life? And what should you value?
I would highly recommend reading this book, and better yet, to watch this lecture, which is free online.
- The 4-hour Workweek by Timothy Ferris - How much could you improve yourself if you only had 4 hours to work a week? To get there you have to do a lot of improvement from the get-go, which is what Timothy Ferris beautifully explains in this book.
If you are looking to get out your comfort zone with hands on challenges, then I would highly recommend this book if only for the Q&A’s (Questions & Actions).
- The War of Art by Steven Pressfield - Fight the resistances, distractions and boring tasks by learning to “dance in the rain”. Life is one big war, how are you going to persist through it?
EDIT: There are plenty more great books but a lot of them are included in the answer wiki already!