1 a: a summons or strong inclination to a particular state or course of action ; especially : a divine call to the religious life b: an entry into the priesthood or a religious order
2 a: the work in which a person is regularly employed  b: the persons engaged in a particular occupation
3: the special function of an individual or group

The definition given on Catholic Answers was simply:  "a calling"

Put all of these together and you get a feeling for what I mean when I ask:  "What is your vocation?"

We all have a calling to labor in our lives for some ultimate purpose.  We  also realize there is true dignity in work.  All of us get down in the drudgery of daily work and loose sight of any meaning.  You can offer this labor for a higher meaning.    By frequently meditating on the calling you are folowing and the reasons for it, we can make the most menial task seem worthy and fullfilling.   Are you a Father, Mother, Brother, Sister, Son, or Daughter?  Are you a boss, mentor,  Catechist spiritual friend, or RCIA leader.      All of us know of people who lived difficult lives of labor in service to others.  You wonder why they just didn't walk away from that and just take care of themselves.  They had found their true calling, their true vocation in sevice to others as taught by Christ.

What is it in you life that you are working for?  What is your vocation?  For a great meditation on a man's journey and always answering his calling please read the article from Randy Hain that gives great witness to this subject.

TCP

All the ways of a man may be right in his own eyes,
but it is the LORD who proves hearts.
Proverbs 21:2