For me, passion is the engine that drives a project to completion. I have many boxes of models that , once I figured out how I wished to modify the model to accomplish what I want, if the passion is not there anymore, back in the box it goes until the drive returns. Sometimes it never does. There is a challenge to figuring out how to modify a kit or attempt a new skill , but the interest to complete the project must be there to drive the process to the end. This is how it is for me, it may be different for someone else.