The definition of Boss is a person in charge of a worker.
Normally we attribute that title to a manger or superior in the hierarchy of the company, but you don't have to be the Boss to be in charge.
Having agency with your own life, the capacity to influence your own thoughts and behavior, to make meaning and purpose from your environment, that is the finest definition of being in charge. Being in charge of yourself, your work, your Efforts.
That is the ultimate BOSS.