Project management lore is full of tales of project managers who were able to take the hand that was dealt and turn it into project success. For you to succeed, you'll have to rely on your ability to coach, mentor, and motivate, in order to get the level of performance you need from those assigned to work on your project.
What will you have to know as a project manager? Well, you'll have to know a little bit about just about everything. You'll have to learn to pay attention to the details, but not get wrapped up in them. You'll have to make countless decisions with insufficient information and despite conflicting signals. You'll have to condition yourself to seek acceptable solutions, rather than perfect ones. You'll have to blend technical expertise with a keen sense of human nature. You'll have to handle administrative matters.
While you're busy doing your own thing, you'll have to cultivate and maintain a smooth working relationship with many other people, both inside and outside your organization. Unfortunately, as you seek to carry out the objectives of the project, it's unlikely that everyone you encounter will be an ally. Organizational politics and reality dictate that not everyone will like project management or project managers (that's you!). Many people will admire your role, respect your position, and appreciate your involvement; others will not. You will need to figure out who's who, really fast.