I have written previously about the link between exercise and mood, including the consistent research finding that aerobic exercise is just as effective in treating depression as either psychotherapy or medication. This week, I'm excited to share a new multi-national research collaboration that I was able to participate in, looking at the mood-exercise linkage in a different way. In this just-published article , a German research team conducted a within-person meta-analysis, meaning that they merged raw data from 69 different studies across 14 countries to draw overall conclusions. Each of these studies (including one of mine ) measured exercise parameters using an accelerometer -- either a research-grade device like Actigraph, or a commercial-grade tracker such as a Fitbit, AppleWatch, or Garmin wristband. Each of the studies also collected daily survey data on a measure of mood or subjective well-being. The combination of daily exercise tracking with daily survey data al...