There are three aspects of being a member of a group, team, or organization, particularly in the domain of knowledge work.
Some parts are prescribed, others created, and others discovered. How well-proportioned or closely-mixed those three are varies based on the group and may change over time within a group.
The parts that are prescribed to you probably consume most hours on most jobs. The group needs you to do things: attend meetings, make and execute plans, run the systems, provide and receive feedback, whatever it may be. “Do your job” usually means “do the things we know we need you to do and pay you to do.”
The parts you create give the greatest autonomy and represent the most obvious place to make changes. This is where a person can intentionally, in advance, define the role. Some jobs leave almost no room for this, others actively encourage it, and most are in between. I’m fortunate to be in a place that’s heavily biased toward experimentation.
This overlaps with the aspect of a job with the potential for surprises: discovery. A person being proactive in a role, actively hoping to advance a group’s cause, and willing to step out of their comfort zone will probably discover new options in a role that they can’t imagine in advance. By contrast, someone else might find that their role diminishes because of lack of work, interest, or passion. In an organization that is open, changes rapidly, or is new, discovery may be a large portion of the work.
I’m still working out the balance of these at my current workplace. Open communication can clarify each of these and how they intersect.