The perceived meaningfulness of one's role and one's activities is to a large degree what gives value to a person's life. It is what reinforces a person's integrity and happiness.
Meaningfulness is a very subjective thing. Essentially nobody can decree what will be a meaningful role for you. It is not that there are certain jobs that have inherent meaning. Rather, it is key that each person is allowed to find their unique role, the particular niche that they are inspired to pursue.