Brand, says Speak, means "consistently delivering distinctive value to customers." It is far more than just marketing, which he illustrated as the tip of an iceberg: the part under water backs up the image we see. You could view your personal brand as your reputation, but Speak broke it down into three principles:
Perceptions: relationships are based on interactions and perceptions. It is up to you to manage the gap between how you want to be perceived and how you are perceived.
"It isn't what they say about you, it's what they whisper."
Value (with three points):
Be distinctive; this takes courage.
Be relevant; this requires empathy and insight.
Be consistent; be disciplined and committed.
Make a difference: "its not about being different, but about making a difference." Otherwise, who really cares about you and your "brand."
I'm no Einstein. Developing a personal brand is a lot like coming up with your own mission statement, something I did as an exercise in a "7 Habits" seminar years ago (habit 2). Finding your own values and sticking to them can do a lot to build a strong brand. For each of us, of course, our values, strengths and preferences are different, and Speak explained he is not trying to make everyone in one mold, but to guide people to what their brand is. If you're messy and unorganized, you wouldn't brand yourself as clean and neat, but instead as creative and out of the box, etc. Einstein was a great example of this, definitely not a typical clean-cut business person, but with a very strong personal brand for his genius.
Speak went on to compare personal brands to product and company brands and explain how we should try to match our own personal strengths to our businesses' strengths in order to create the most value for ourselves and our organizations. There's a lot I left out, but he does have a book and a blog if you want to learn more!