In Raluca Gavriloae's site Morning Solitude, there's an article from three years ago about finding your true calling and a foolproof method for it. The site seems to have quieted down since then but the message of that particular post stays true: if something stays with you and keeps nagging at you even if you tried to ignore it for however long, that's what you should be doing.
This does NOT mean that once you take the leap and surrender yourself to that cause, you won't have any struggles with it.
I'll use myself as an example but I'm sure I'm not the only one who deals with this. I'll get up in the morning, think about whatever I'm working on at the moment, and the fear kicks in. I fear sitting down to do the work, because there's a chance I don't know how to do it anymore. And even if I still knew how to do it, what if it wears off? What if I'll be wasting the little talent I have on something unimportant, minuscule, juvenile?
Some days this fear keeps me from doing anything meaningful until 8.30 in the evening, at which point I absolutely have to do something to prevent the day going to waste - while realizing that every day that I postpone the work until the evening, a large part of the day is going to waste.
Whenever the fear of the main work feels to exhausting, I practice fear swapping: I do some secondary work to feel like I'm achieving something. It's somehow easier. But it's not the same.
I know, rationally, that my fears are irrational. I know I can become better only by facing those fears and working more. But the more I don't work, the bigger the fear gets, and the less I become better.
Note to self: just try it. See what happens. You could die in your sleep tonight - do you really want to risk leaving the story unfinished just because of some stupid irrational thing?
If you knew this was your last chance to do your work, no fear could stop you from doing what is needed. So why risk it?