The placebo effect is a well-known, well-accepted phenomenon, most traditionally thought of as a sugar pill–an inert, ineffective substance that nevertheless has a positive effect on an illness. The underlying mechanism of action is assumed to be belief in the remedy; the power of suggestion is at work.

Needless to say, from a strict medical viewpoint, the placebo effect falls into the category of muddy, unsubstantiated, mumbo-jumbo. It’s an attractive idea, but not worthy of any more consideration than the friendly pat on the head you might give to a lovable but annoying puppy. Two new studies have raised a big “who says?” regarding this attitude.

In one study, researchers followed first year law students, monitoring their optimism in general, expectations for academic success, and immune system function. Students were actually injected with substances that would trigger immune system response. Having an optimistic outlook in general was not related to immune system function. But actual expectations for success and immune system activity were directly parallel. When students felt that their performance in law school was potentially successful, their immune system function was much improved. And the opposite was true: fearing you were about to fail meant your immune system was compromised.

In the second study, study participants were followed over twenty-eight years. Subjective well-being–a concept made up of positive feelings, overall life satisfaction, and life satisfaction in the moment–was assessed at multiple points in time over the course of the study. Subjective well-being–i.e, being happy with your life overall, and expecting that all is well–contributed to less risk of illness and greater longevity. People simply lived longer when they were satisfied with their lives. This life satisfaction is akin to what Gretchen Rubin calls the sense of “living the right life” in The Happiness Project.

The placebo effect, i.e., the expectation that the remedy will work, is accepted to account for about 35% of a treatment’s effectiveness. These studies suggest that expectation is a much bigger contributor to our lives than that. Perhaps it’s time to regularly check in with ourselves about our expectations, and adjust our lives accordingly, taking control of whatever elements we can so we can live the life that feels right to us.