The concept at the heart of all of Sinek's work is demonstrated by the Golden Circle below:
This is a simple concept but clearly so often overlooked. How then are we able to take advantage of this quirk of biology and increase our success? The first stage is obviously clearly defining your why. What is your purpose? the thing that gets you up in the morning or that you keeps you at work til late, the thing that you want to tell everyone about? As discussed at the start this works on both a personal and business level (for the personal level I recommend checking out the Steve Peters 'stone of life' exercise) and hopefully will come easily to mind. If not it may be time for tougher questions.
The second stage is then aligning your what and how with that why. The why is just a belief which is something that can only be made real by the actions that prove it. This means that your products, your marketing, your staff, everything needs to be aligned with that why. This alignment balances your golden circle and creates authenticity. People buy authenticity.
Getting this piece right can be defined by two simple tests. The celery test and the bus test. The first dictates that what you believe should be clearly identified by what you do. This filter should then be able to be used by everyone in an organisation to make the best decisions. Imagine sending someone to the supermarket to get some food, what random selection might you get? Compare this to if you are someone who has a clearly defined why about looking after your health, that person would be able to make more accurate selections that are aligned with the why. The second test applies to leaders - if you were to be hit by a bus tomorrow how much would your team or organisation change? Would those taking over have a clear sense of direction and an obvious filter for making decisions? If not then the why needs to be made clearer.
And that is as complicated as it need be. The book explores how Apple and other successful companies have used their why to achieve massive business success. If you're interested in the nuances of this then read the book. If not simply watch the TED talk (below) and keep a copy of the Golden Circle close to hand. You'll be surprised by how effective it can be for aligning your decisions and increasing your impact.