An interest in supervising other workers would be useful for someone who wanted to become

An interest in supervising other workers would be useful for someone who wanted to become a Manager

Explanation:

A manager is person who manages work, people and who is the most responsible person in an organization. A main duty of the Manager is to focus on to allot works to their sub-ordinate, monitor the work done by each and everyone; encourages the employees who are transforming their career very well and showing their good attitude towards their work; analyze how employees cooperate to achieve the target and plan for future targets.

So a Manager monitors or supervises others work.