Following our bliss, what is it?

I say, follow your bliss and don't be afraid, and doors will open
where you didn't know they were going to be.
If you follow your bliss, doors will open for you that wouldn't have opened for anyone else.
Joseph Campbell, 1904-1987

Great quote but how do we know what our "bliss" is. 

What happens when what we think makes us the happiest really hurts us in the long run? 
How or where are we able to get the courage to actually step off the cliff and know it is the right thing to do.

I always had the idea in the back of my head,  I wanted to be a writer, but fear always stoped me.  I enjoy writing and can actually write about anything.  At my 'real job' I am always given the task of doing the 'creative' writing when needed.  Of course I never think it is good enough.
I do not think I could write a book seems to long and tedious for me.  I am thinking short stories where I can finish it in one sitting and not loose track of the story line. 

But is that my bliss?  Is that the path I am supposed to be on. I do know all this pain I feel should be for a reason other than the pain itself.  Or is that what we are led to believe?
Really the question should be 'what is bliss.'  Because does anyone really know?
If we follow our 'bliss' will it really lead to happiness?

And then back to the question "What really is our Bliss?"
I think when we are able to answer that we have found it.