Placebo

I've typically operated under the assumption that the placebo effect is ubiquitous, pervasive to the extent where not a thing happens in our minds that does not directly affect our entire bodies. I'm talking about 90% of our individual physical realities are completely mental.

When I was just a teenager, having just learned about the placebo effect, I was convinced that simply thinking about the destruction of my cold virus was more effective in speeding up my recovery than chicken soup or any other remedy available. I've never since had a horrible, debilitating cold.

I just stumbled on this NYT article here, found via metafilter, which seems to provide evidence that, regardless of the amount of physical exercise you actually do, what really influences how fit you are is whether you think you're getting exercise.

And the evidence piles up.