The Four Agreements by Don Miguel Ruiz. This book is easy to read but the learnings and wisdom you will get from this book are inspirational.
The Four Agreements in the book are:
1. Be Impeccable with your words
2. Do not take anything personally
3. Stop making assumptions
4. Always do your best
I still find it challenging to apply these agreements to my daily life, but they serve as important reminders for me to become a better person every day at work and beyond work.