Take a look around in your workplace. Are you smarter than most of the people there, or are they smarter than you? If you're young and looking to learn then it's a good thing if most of the people there are smarter than you, or at least have skills or attributes that you'd like to learn. If you're young and this isn't true (there should be at least a COUPLE of people you feel you could learn valuable skills from) then you're probably in the wrong job.
Another important question to ask yourself is... am I mainly in this job to learn or earn? If you're an inexperienced salesman, for example, learning should be around about as important to earning to you. Think of sales skills you learn as having a monetary value and that will inspire you to learn more.
But if you're an experienced salesman, do you really need to learn the same things over and over again? No. You should be looking to push your comfort zone and learn new things. Good news- in MOST sales jobs, there will practically always something new you can learn about the product knowledge, either that of your own product or of your competitors. Use your work mates as a resource too- if you're in good worksplace there will be much you can learn from them.
Say you're working online... your fellow employees can be anyone you know from forums or who you have on msn. There's a massive amount you can learn!