Listening to God's Call

I went to a talk by a missionary couple on Sunday, and something that the speaker said stuck me-
He said people don't leave the missions field because they have heard the wrong calling. Sometimes it is not because of wrong calling, but because of our immaturity. Inability to handle hardship, and challenges. We face even more spiritual warfare on the missions field. And we must pray that we will only leave when God calls us to leave.

Another thing-
People don't pray about becoming engineers or doctors. Society says that these are possible paths to take, and so we just study engineering in the university.
Why do people then pray about becoming missionaries? The truth is that whatever route we choose to take, we must be called. If people will really listen, much more people are called to go into the missions field. Its not because God hasn't called, it is because people are not listening.

Would God fault you for doing something voluntary for Him? i.e. saving souls in the missions field?

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It was quite thought provoking listening. And thought that perhaps I should start asking and praying again about the future. I'm on a 2 year contract here, and I've finished 9 mths plus. Not sure what's next.
The question again is about the general calling vs the specific calling.
General calling being- Go forth and make disciples of all the nations. God has already called.
vs the Specific calling of where to go, what to do, when to go etc.

With God's blessing of a wonderful gift recently, I am thinking if he may indeed be leading me towards being based in the missions field.
May we have the courage to pursue what He called us to do.