Conscious breath control is a useful tool for achieving a relaxed, clear state of mind.

You've got to experiment to figure out what works.

The most common objection that I hear to walking as exercise is that it's too easy, that only sweaty, strenuous activity offers real benefits. But there is abundant evidence that regular, brisk walking is associated with better health, including lower blood pressure, better moods and improved cholesterol ratios.

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.

I think integrative medicine, something I've pioneered, is the way of the future. Its great promise is that it can reduce healthcare costs by shifting the whole focus of healthcare away from disease management to health promotion and prevention. They can do that two ways: first, by focusing attention on lifestyle medicine, which is very deficient. And second, by bringing into the mainstream treatments that are lower cost because they are not dependent on expensive technology.

Another very common use, in all cultures, of psychoactive substances is to give people transcendent experiences. To allow them to transcend their human and ego boundaries to feel greater contact with the supernatural, or with the spiritual, or with the divine, however they phrase it in their terms.

The desire to transcend one's own ego boundaries, to share completely, even for a moment, the consciousness of another person must be a universal longing. It motivates many of our activities from taking drugs to making love, and lies behind the search for new ways of getting close to one another that is so intense in our society today.