Ki =気= chi'i, spirit

Mochi = 持ち = to have something, to hold

Kimochi = 気持ち = a feeling or emotion

I'm trying to think when kimochi means something other than feeling or emotion but no examples come to mind right now. You can say things like "ki no mochi you" (気の持ち様, which refers to your frame of mind and essentially means your spirit dictates your experience (ie. you create your own reality, or more cynically, "you're making it up in your head, you freak!").