- The 7 habits of highly effective people by Steven Covey. This is a classic which every person interested in leadership should read
- Made to stick by Chip & Dan Heath. This is about communicating ideas so that they stick with your audience. Naturally this is also a big topic for Project Managers
- Influence by Robert B. Cialdini . A classic with tons of useful information about how "influence" works
- Getting past No by William Ury. If you want to learn more about negotiating this is the book to start with.
- Drive by Daniel H. Pink. Explains what drives people. If you want to learn more about Motivation this is a good book to read.
- Mojo by Marshall Goldsmith. He is a famous advisor to business leaders and this book is about how to achieve happiness and meaning in our lives.
If you read these books and apply what you've learned you will be more successful. But keep in mind that just consuming them and then forgetting about them doesn't help. You have to take some time and really apply the advise that works for you and your situation.
If you want some advise on relaxing (especially for high stress jobs) I would suggest one book by Thich Nhat Hanh like "Peace is every step" . This can also help in business situations by learning to focus on the moment and not getting distracted.