John Keating, played by Robin Williams in the film Dead Poets Society states, "Carpe diem. Seize the day, boys. Make your lives extraordinary." According to Wikipedia, the American Film Institute ranked this line number 95 in its list of the 100 best quotations in American film history.
The idea of seizing the day is good advice for a good reason- taking advantage of the opportunities life puts before you each day is central to succeeding in life as well as in your career.
One way to put this into practice is not to let your job title limit you. Too often a worker fails to step up to the plate in a vital situation because they do not have the word manager, or supervisor in their title.
If you have the knowledge and skill to improve a situation, put yourself forward and get the job done. Your boss will notice and see you as a competent member of the team. as long as it is done with tack and you are not grand standing or showing up your immediate superior it will help you career rather than hurt.