Start With Why made me rethink all that I do and especially why I do what I do. Here is a short insight about the book.
Who is the author?
Simon O. Sinek is a British-American author, motivational speaker and marketing consultant. He is the author of four books, including Start With Why. His talk How Great Leaders Inspire Action is listed as the third most popular TED presentation. 
Who is this book for?
Start With Why is for those who want to inspire others and for those who want to find someone to inspire them. 
What’s this book about?
Why are some people and organizations more innovative, more influential, and more profitable than others? Why do some command greater loyalty?
In studying the leaders who’ve had the greatest influence in the world, Simon Sinek discovered that they all think, act, and communicate in the exact same way-and it’s the complete opposite of what everyone else does. People like Martin Luther King Jr., Steve Jobs, and the Wright Brothers might have little in common, but they all started with why.
Drawing on a wide range of real-life stories, Sinek weaves together a clear vision of what it truly takes to lead and inspire. 
My favourite quote
“The people don’t buy what you do, they buy why you do it.”
Should you read it?
In conclusion I would definetly recommend the book for you to read. If you already read it share your favourite quote in the comments section bellow.