The importance of knowing yourself should not go underemphasized. The sooner you can find out what it is that makes you happy and what you can be passionate about, the sooner you can go after it with everything you've got. Some important questions to ask yourself are: 

- What am I good at and what do I like to do?

- How do I make important decisions and what do I value?

- What important life experiences have I gone through, and what can I learn from them?

- What is it about people you look up to that makes you aspire to be like them?

To sum up the message of the video: Surround yourself with amazing people and find the thing you can't not do. Discover what that is so we can inspire ourselves to take action and do what we love, to inspire others to do the same.

There is no one who embodies that more than my younger brother, who recently sent his video submission for a scholarship. Please view the video to see a living example of these principles!

https://www.youtube.com/watch?feature=player_embedded&v=jpe-LKn-4gM

http://www.youtube.com/watch?feature=plcp&v=GDhU4t1pgV8

EDIT:

Update: Here is my brother's keynote speech at the National Space Club's 56th Annual Goddard Memorial Dinner http://www.youtube.com/watch?v=cn9I4kEFO60