Waiting (or trying to force yourself) to feel motivated is the absolute worst enemy of getting stuff done. I don't ever "feel motivated" to do laundry, but I do it because otherwise I won't have any pants. If you take away the expectation that you need to feel inspired or excited about decluttering or organizing, you also take away some of the perfectionist pressure that constantly obstructs any progress. When you start to feel yourself resisting a task ("I just don't feel motivated right now."), shrug, say "OK, but I'm just gonna go ahead and get started anyway." When you make the choice to do something instead of waiting for a magical sparkly feeling, YOU take control. And that's pretty motivating.