What's Your Toughest "Thing"...?

What's your toughest thing in regards to writing? My hardest "thing" is always the first draft. Writing those words for a new novel leaves me shaky, uncertain, terrified and results in gnawed fingernails. Yet just like a roller coaster—the deadly anticipation, the downward rush/fear—it's a thrill. How can I love something that's so hard to do? Damned if I know. 

How about you? What's your hardest "thing" when it comes to writing?