This study demonstrates that the ergonomic analyses of work must consider why a worker adopts certain movements (gestures) when performing assembly tasks. It discusses the balance between allowing the worker to freely choose the way of assembling goods and providing guidance. On two assembly tasks in a furniture manufacturer, this research performs an ergonomic analysis in which worker movements are emphasized and it investigates the impact of these strategies on the ergonomic risk and on the worker’s health. Data collection instruments included direct observation, unstructured interviews and film footage. The ergonomic analyses show that the work environments are ergonomic, but workers adopt their own movements, unaware that these are awkward postures. Guidance proved to be effective in improving ergonomic risks. This article highlights the significance of understanding work movement, its implications in the corporate training programs as well as in the ergonomic risks and in the worker’s health.