It's not enough to just work hard -- people have to notice
In college, your grades are determined by (normally) static and universal metrics: test scores, term papers, attendance, maybe class participation. In the workplace, things aren’t so black and white. What’s the metric to grade a food runner? And if no one complains, how you can even really tell if a server is doing his/her job?
Knowing what your place of employment cares about, and excelling at it noticeably, will get you on the radar of the people who matter. If you can do it all with a positive attitude and a passion for what you are doing -- even if it does entail scraping empty oyster shells off the bottom of chair cushions -- you possess the attitude and aptitude a manager craves.
The workforce is filled with middling employees who work tediously, and have no idea how to showcase their efforts. Intangible skills and subjective opinions of superiors is just as important as producing results, maybe more so. I was promoted three times at that restaurant, mainly because I knew what mattered, and the right times to prove it. Sometimes that meant staying an hour after we closed to help clean up, or coming in an hour early to stain new tables. Combine this method with nepotism for best results.