By keeping my hand in that, it's the way I keep learning. The main way you learn in medicine is by practicing and working with patients.

To be clear, I worry as much about the impact of the Internet as anyone else. I worry about shortening attention spans, the physical cost of sedentary 'surfing' and the potential for coarsening discourse as millions of web pages compete for attention by appealing to our base instincts.

Gardening is not trivial. If you believe that it is, closely examine why you feel that way. You may discover that this attitude has been forced upon you by mass media and the crass culture it creates and maintains. The fact is, gardening is just the opposite - it is, or should be, a central, basic expression of human life.

In the world at large, people are rewarded or punished in ways that are often utterly random. In the garden, cause and effect, labor and reward, are re-coupled. Gardening makes sense in a senseless world. By extension, then, the more gardens in the world, the more justice, the more sense is created.

Prayer's important, not just as some kind of a metaphysical exercise, but I think it's a way to refresh one's own mind and motive. If you're praying, you're really looking beyond your own personal thoughts and the pressures that are around you.

Observational studies show that exercise, nutritional supplements and reducing psychological stress can help. Chronic high stress and smoking can lead to accelerated telomere shortening.

If there's a seminal discovery in oncology in the last 20 years, it's that idea that cancer genes are often mutated versions of normal genes.

I welcome nonviolent protests as an exercise of our great democracy.