I think regardless of what you do, you'll always end up hating some part of it, especially if you do it for a really long time.

I've been writing for a really long time, and it does get harder to press your craft forward. It use to be fun to discover new ways to represent ideas, better ways to write descriptions, etc. But these new discoveries use to happen on a daily basis. Then weekly,then monthly...

Like arenasnow said, thinking about the destination helps. I've stopped making characters with really cool endings and have instead started making characters that can have interesting reveals much earlier on. 

I have a love hate relationship with collab. I hate how slow some of my partners are at responding, but it's really fun to write something and take turns stringing the scene along. Not so much with fights, but try having a character ask another character an awkward question. Preferably one that you don't really know how they will respond to. You'd be surprised the kind of joy that can bring you.

Lastly, I convince myself I do actually love the writing. I tend to proof my posts before submitting them, and it's so much fun for me to replace words or restructure paragraphs. I love editing, so I don't worry about writing really good the first time anymore.