Endings

I would venture to say that I have the first half of my book plotted out relatively specifically.  I have the next quarter plotted out a little less so, depending on some of the things I choose to do in the first half.  I am consciously leaving the ending a question mark for the time being, for a couple of reasons.  One, as with the third quarter, it will depend on what happens to that point (obviously).  Two, I have plotted out entire novels and then didn't feel like writing them because it didn't feel fun anymore.  Maybe if this one goes well, I'll drag those out and see what I can do with them, because I do love the storylines and complexities that took a lot of thinking to work out.  But for now, I'm trying to keep this one fun.  Will I hit walls where it stops being fun?  Heck yeah, writing is hard.  The actual work of it.  But I can't wait to start what I'm working on now.(I'm being held up a little by the research, as I mentioned... the very first chapter requires knowledge about something that I needed to dig into, but I'm almost ready).  So for now I am not spoiling my own fun by ruining the ending... I'm going to let it work itself out.

So for any of you who write (and I'm sure some of you do, you are creative types)... tell me.  Do you plot out your endings or do you just let them unfurl?