I've got a loooooot of model kits to build. And I've got too much half built but I discovered something 3 years ago : limiting the choices made you a more inventive person.
Since I didn't have that much of model kits around me (surrounding me ?) I needed to build with what i've got in my hands. Even concerning the tools...
But when I lack motivation, I step aside and try something different, with another model, or even drawing, taking back another project. It's a never ending story I presume
Same thing when you have to wait for a part to dry after painting, of putty to dry... Working on something else. Always keeping busy.
As a matter of fact I discovered something else this past few months : I can't watch TV anymore. Since it's rubbish, don't really care (it's numeric format, no more radio-waves Secam channels) but I kinda like to have something in the backgroun to accompany me when building my Kitbashes and such... I was really inventive with bad TV programs actually and I can't really explain it... It's like doing something and listening to Radio, or a pop song. It's not the same with a DVD playing on TV, or Itune music on...
I also tried to motivate me working with other fellow modelers. Didn't worked well, or in 100% efficiency manner. But I sure was inspirated by other dudes work and experience, that's for sure.
All in all : just glue it !