Not in the mood, disinclined.
I didn't understand why my sister was reluctant to go see the movie, but after seeing it, I understood.
The strong urge to not do whatever you had planned (or what had been planned for you) with or without valid reasoning. Often fails to prevent the occurrence of said plans.
Creep: "I has candy get in van."
Kid: "I'm reluctant, even though I have a tazer."
Wife: "Are you ready to go to a movie and lunch and my parent's house and the dog park and haircuts and ice cream and the musical theater and be too tired for sex?"
Toolbox: "I'm reluctant, as none of that was things I want to do, but you do have my scrote in a vise. Lets go."