You can stick to your job description, get paid for it and go home, no problem. But successful people tend to think beyond themselves and don't limit their contributions to what is defined in their job description or only to the tasks they are allocated. Of course, you have to do your job well, but do it so well that you have free time to think about how else can I add value? how can I make the life of my boss a bit easier? Remember the folks you report to have a lot of burning fires to put and if you are able to lend a helping hand, it will go a long way. You will not only be seen as a reliable person and team player but also called in and given responsibility for important, mission critical assignments in the future. And only when you get to do the hard stuff do you grow. Guess what, soon enough you will strongly differentiate yourself from your peers.