misbopeep - vocation may once only have applied to a religious calling or a sense of doing good for mankind, but it doesn't any more - there are too many opposing views as to what is and isn't for the intrinsic good of mankind these days and as to whether God exists and can actually therefore call you to do anything... It can mean no more, no less than a strong feeling of fitness for a particular career or occupation. It may well also in most peoples' minds require you to have a high degree of dedication to it, regardless of the level of pay. All this applies to many pilots, and train drivers and astronauts, hospital cleaners, even bankers and all sorts of other people. You could argue, anyway, that a hospital cleaner or road sweeper can have a vocation, because clean hospitals and un-rat infested streets are for the good of mankind in more than just their own minds. We all think these things are good.
Teaching is not a vocation for everyone who enters into it. For some people, it is just a job. Some people may say that being a vicar or priest is not for the intrinsic good of mankind, they might even say what they do is bad for mankind - that doesn't stop a vicar thinking he has a vocation...