The plight of an author

So here I am rewriting a few last scenes of my novel. I'm close to done. I get an idea. It seems good. It explains why my protagonist throws himself into a dangerous situation close to the end of the book.

I could tell you more - but I don't want to spoil it for you. I get this great idea. It seems thrilling. I ask myself - Should I include it? Then I say - This is a Thriller do it. 

This my friends is the plight of an author. Always creating, but at the same time trying desperately not to screw up what you've spent years already creating.