This definition is a kind of secular translation of what began as a religious concept. The Catholic Church, in particular, equates "vocation" with a "calling from God," often a calling to the priesthood.
Quakers talk about "concerns," or "leadings," which the book of Faith and Practice, published by the Pacific Yearly Meeting of the Religious Society of Friends, says are "the experience of feeling called by God to act."
Bob Dylan, who surprised people when he began manifesting a lot of interest in, and knowledge about, Christian theology, puts "vocation" in what I consider to be exactly the right context:
Leave your stepping stones behind, something calls for youDylan makes it clear: to answer the call, you have to leave the past behind, and start anew.
Forget the dead you’ve left, they will not follow you
The vagabond who’s rapping at your door
Is standing in the clothes that you once wore
Strike another match, go start anew
And it’s all over now, Baby Blue
And of course, before you can hear the call, you have to listen.
Are we listening, yet?