Here are some of the most common ways that your perspective might change after becoming a manager.
Turnover isn't necessarily bad. Employees tend to raise their eyebrows every time a department loses an employee, but managers often see it differently. Most managers really care about retaining great employees, but care far less about retaining others. And some they're downright happy to see leave, even though they might not let on to others.
Bonuses and raises are retention strategies, not rewards. Employees often feel entitled to an annual bonus or raise in exchange for good work, but these things aren't rewards for a job well done. They're given out because the company wants to retain good employees. If a manager knows that an employee is going to be leaving the company soon (because she's going back to school, for example, or has accepted another job), that bonus isn't likely to materialize—because at that point retention isn't possible.
Not every position is designed for growth or satisfaction. To employees, it often feels obvious that employers should provide growth and development opportunities. But not every position is designed for that. Some roles are fairly rigid by their nature and don't have any room for advancement (because the other roles on staff require different experience or skill sets). Many managers are perfectly happy to hire people knowing that they'll only stay a year or two and then move on when they get bored, and they don't feel obligated to try to keep them fulfilled beyond that. (They should, however, be upfront with job candidates that this is the case before hiring anyone. It's wrong to blindside people with this after they're already on the job.)
"Other duties as assigned" covers a lot of turf. Whether your job description contains that "other duties as assigned" clause or not, most managers are going to expect you to pitch in as needed. That could mean anything from covering for an absent colleague to helping the CEO with a pet project that's totally unrelated to your core duties. Managers view you as being there to help the company achieve its goals, and the best way for you to do that can change on occasion. You can certainly speak up if you object, but it's not always going to be negotiable.
No matter how pressing a problem is, something else might be more important. Employees sometimes wonder why on earth their manager isn't paying more attention to a particular problem, whether it's a slacking employee or a budget issue or difficulty getting what you need from another department. But when you're a manager, there are tons of competing issues that you could spend your time and political capital on—from getting your staff raises to killing an unproductive program to adding a staff position to your team. Good managers quickly learn to pick their battles. It might look like they don't see the value in advocating for something you want, but in many cases, they do but have made the judgment call that something else is a higher priority to focus on right now.
Managers don't remember everything you're doing, and we don't need to. Employees sometimes get annoyed when it seems like their boss has forgotten details of what they're working on. But managers have to remember all the details of their own work, plus the basics of what a whole team of people are doing, so don't get irked if they need you to remind them of context or a key detail. It doesn't mean they don't care about your work; rather, the reality is that they can't keep tabs on what every employee is doing every day. (That also means that you shouldn't resent it if you need to remind your boss before your December performance review of what you achieved back in February.)
Attitude matters a ton. The reality is that being a manager is hard. When people make the job easier by being flexible, professional and pleasant to work with, a manager is more likely to reward them. And when someone is difficult to work with, it doesn't matter how good the rest of their performance is—the price of keeping them on staff is often too high.
Alison Green writes the popular Ask a Manager blog, where she dispenses advice on career, job search, and management issues. She's also the co-author of Managing to Change the World: The Nonprofit Manager's Guide to Getting Results, and former chief of staff of a successful nonprofit organization, where she oversaw day-to-day staff management, hiring, firing, and employee development.