You know you really want to get something over with when ...

1. There are MINOR changes which could easily be done by the client and would probably be changed by the client anyway and you don't want to do it anymore.
2. There are times when you just want to finish the user manual and give it already.
3. You don't want to hear about any other changes. AS IN. No more changes if possible. So you could already move on to the next project.

Now dealing with all those symptoms is difficult sometimes but you just have to.
1. Email the client, that, yes, you're going to be working on it and it's no biggie. (Well, it's true. It's not biggie and you could really get worked up on it sometimes because you don't feel like it anymore. Simply that. Mainly that.)
2. Set a goal as to when to FINALIZE the manual and hand it in already.
3. Breathe in and out. Be calm. Think of chocolates. Think of teddy bears. Think of Picross, Sudoku or other fun games on your gadget or laptop.  Then just be prepared for the next few emails.

Now if you're female and probably having some degree of PMS during the time this hits you, I can't suggest anything at the moment. Mood swings are difficult to handle, that's it.  I say Good Luck, girl, when the time comes and you'd probably wing it anyway. Somehow.

Now smile and be happy. :) Just less than a day and a half it's already a weekend.