I think if you have intrinsic motivation to work on your hobbies, it won't feel like work and you will find a way (unless you are actually extremely exhausted -

I think if you have intrinsic motivation to work on your hobbies, it won't feel like work and you will find a way (unless you are actually extremely exhausted - then the fix is to rest). 'I feel like I’m missing that spark' sounds like you don't believe that working on that project is beneficial. http://mindingourway.com/guilt/ http://mindingourway.com/guilt/ helped me to discover my intrinsic motivation. But you might end up doing something else instead of your original hobby.