The aim of this article is to present Stefan Szuman’s opinion on the sources of motivation in children and adults. The problem is still present in psychological discourse. Stefan Szuman undertook to resolve this issue in the first half of the previous century. His explanation has served as a foundation for many contemporary theories (e.g. intrinsic motivation, locus of control). It may still be considered a valuable source of inspiration for further studies and discussions within the field of contemporary psychology. Drawing upon Szuman’s works listed in the bibliography, the article is an attempt at presenting his reflections regarding the function of the child’s attention and the role of attention in the mental control of the adult person. The paper discusses the mechanisms governing the creation of internal and external motivation and their co-relation. In his research Szuman pointed to the complexity of the child’s motivation and to the deep existential dimension of the child’s cognitive activity. He juxtaposed child’s primal joy of action and cognition with the adult affirmation of life. The juxtaposition which connects the motivational basis of the child’s cognitive activity with the adult search for some deeper meaning and sense in life seems to place the issue of motivation within the broader context of orthogenesis, among other problems concerning the continuity of changes constituting human development. At the beginning of the previous century, Stefan Szuman analyzed the process of growing up in the context of the entirety of human life.