In the following sentences, I have a couple of questions.
Could you explain why the second sentence starts with “That”
I think “That” connects the first and second sentence. But, I’m not sure how the second sentence (That if you…) connects to the first sentence (How much of this is a passion…).
you walked away from what?
How much of this is a passion, and how much is this a duty you feel? That if you walked away, you would be walking away from something that is more important to the world than just yourself?
The first sentence and the second sentence are tied together because the second sentence is referring to whether or not the guy feels the job is a duty.
So in other words, you could re-word it to something like this:
How much of this is passion, and how much of this is a duty that you feel if you walked away, you would be walking away…
It’s just that they turned this into two sentences instead of making it a more compound, possibly run-on sentence.
It starts with “That if…” because this is more representative of how the speaker expressed the thought. In formal writing the second sentence would be considered incorrect. To make it “correct” someone would have needed to add or subtract words. I think it’s fine how it is since people regularly speak that way.