Randy Pausch was a university professor, meaning that his job entailed helping others to achieve their aspirations. In The Last Lecture, it is clear that this was always a vital aspect of his vocation. However, when he discovered that he only had a short time to live, enabling the dreams of others became doubly important, since his own dreams were no longer achievable in the long term.
Pausch talks at some length about his relationship with his wife, Jai, whom he describes as the central figure in his life and who would therefore have been the person who did more than any other to enable his dreams. Although there are many ways to enable the dreams of others, one common factor is likely to be the use of one's own special skills and talents to supply whatever help and knowledge is needed for them to fulfill their potential. Pausch did this both as a professor and, on an even wider scale, as a computer programmer with his educational software, "Alice."
It is reasonable to think that almost everyone in the world is involved in some way in enabling the dreams of others. Humans are self-interested, but pathological selfishness (meaning that one is entirely indifferent to the happiness of other people) is comparatively rare. Any parent, teacher, friend, or manager who cares about their role (and many people, of course, fulfill two or more of these functions) is likely to be involved in helping others to achieve their dreams.