Have you ever had to train a new person into a job role (show them what to do) without being asked.
Had to fix a photocopier, fax machine, an important piece of equipment that is in constant use, and been able to rectify the problem.
Had to take control of a situation, maybe when everyone is out of the office/taken calls/direct public/take enquiries.
Had to ever delegate work/oversee a new employee/take control.
Had to do a stock take/initiate a 'clean up'
Had to work within a team/team building exercise
Had to write a report/letters/correspondence (without help)
Had to help in controlling a crisis/argument situation, with good effect.
Come up with, and implemented any ideas, for the smooth running of a department.
Any of the above, would be using your own initiative.
Good luck