It is a fair question, not a philosophical one but a physiological 或者 medical curiosity we wish to answer in relation to how healing is achieved.
Perhaps, 你 may not have encountered the 问题 before. 或者 你 may not think of it as important 或者 worth considering. For why should we bother how we smile 或者 whether it comes from the heart, the head 或者 the kidneys, for that matter. Maybe the whole body “smiles” and feels the happiness all over. It just so happens that the lips manifest that happiness just as the tears from our eyes manifests our sorrow.