Generic encouragement evaporates. *You'll be great* is pleasant and does nothing, because it costs the speaker no attention at all and everybody knows it.
What lands is specific and has a memory in it. Someone asking, a year later, whether you ever sent the application — proving they held on to a detail you mentioned once.
Most people's ambitions die quietly from never being asked about. Being the person who asks is a small role, and there are usually vacancies.