In recent years I have generally refrained from using the term "calling." I'm not sure why. some of it is probably because it feels too sure to me, when I know that nothing is for certain. Some of it is probably that I worry about what "calling" implies. Being "called" seems to imply some insurance of success (at least the way we use it). It's as though being "called" means being given a promise that we'll do something special. The truth of it is, we need not and are insured not to become anything at all other than who we are right now. I am simply called to this moment. My calling in this moment is to be a sacrifice, whatever that means.
We have this tendency, especially those of us in college, to live for our next accomplishment and we tend to replace the word "accomplishment" for "calling." I'm afraid that this mentality is too close to slavery. True freedom is the "freedom to become nothing," I think Craig Keen said that.
Freedom may mean living without a "calling"--without the need to fulfill some divine mandate. We might simply be called, or let me use the word invited, to be ourselves and then to give ourselves away.