As we are all well aware, physical exercise has many positive effects on our health. It also promotes good mental health and there is a larger amount of evidence that exercise protects us from stress-induced depression. A recent study looked at the mechanisms behind this effect and it was discovered that exercise training induces changes in skeletal muscle. The muscle then produces a substance that can break down a chemical harmful to the brain which builds up in our blood when we are stressed. This study could open up whole new ways to treat depression where skeletal muscle could be targeted instead of the brain.