The Internet was appealing partly because it was something I could do in bed and feel like I was achieving something. I had an operation when I was 13 and ended up with complications, so I was in and out of the hospital. The bottom line is you can get through health challenges. It's part of why I was so driven.

I was very down as a teenager, very upset because I had gotten hurt in a car accident. But my dad was a source of strength. He used to say, 'It's the character with strength that God gives the most challenges to.' I've thought about that so many times in my life when things didn't go right.

Let us begin with the fine-structure constant. ... The fine-structure constant is really the ratio of two natural units or atoms of action. ... We obtain action when we multiply energy by time. ... We are challenged to find a unified theory of electric particles and radiation in which the electrostatic type of action and the quantum type of action are traced to their source.

A hygienic environment, proper waste and sewer disposal, clean water and all efforts that destroy disease-carriers like flies and mosquitoes will reduce the spread of disease and promote good health. My home challenge for a hygienic environment is that we should be responsible enough to make sure we are safe and comfortable eating apples in the toilet and bathroom!

Do you have an entrepreneurial spirit in you? How helpful and creative are you in solving challenges? Have you attained communication and negotiation excellence status? Can you effectively market yourself and your service/product? How effective are you at selling your vision? The answers will determine how far your influence will go.

When I think of excellence in motion, I think of the big picture. Because of the magnitude of this concept, I look at it from an aerial perspective. It is a mindset that challenges the boundaries of self-induced limits—that point where you aspire to exceed your expectations, where the mind-body-achievement connection resides and wins time and time again.

The witch who claims to forbear her magick for fear of causing the next Indian tsunami is really saying that she is powerful enough to kill thousands of innocent strangers when all she meant to do was water her mugwort. She can't be challenged to produce evidence of this, because doing could provoke earthquakes and Africanized bee attacks.

I'll co-host 'TODAY' from Los Angeles Saturday morning and then make my way up to Merced for that evening's graduation ceremony. I'm still touching up my remarks, but my challenge to the Class of 2010 will be to break through the deafening and too often negative echo chamber of the digital era and become critical and independent thinkers.

My father taught my siblings and me the importance of positive values and a strong ethical compass. He showed us how to be resilient, how to deal with challenges, and how to strive for excellence in all that we do. He taught us that there's nothing that we cannot accomplish if we marry vision and passion with an enduring work ethic.

I always try to see the good in everything, and that gives me strength. Even when I lost in the London Olympics quarterfinals, I said to myself, 'Don't lose heart, God has his own plans.' Actually, life just goes on; you have to accept whatever challenge you face and become stronger.