I usually have to be in the mood, but when I am, watch out because that's all I want to do! Dinner? Um, no, didn't have time to plan anything--sorry--but there are leftovers in the fridge.
You can't force yourself to be motivated; it's something that just happens from within.
One thing I'm trying this year is to break a quilt I want to make into baby steps. I committed to making 10 snowball blocks per week. So far, so good! Once all the blocks are done, I've committed to sewing one row together per week. That way, I don't get bored with it or burned out, and by year's end I'll have a finished quilt. When you partition the various steps of quilt making into smaller components like that, it may help you to feel more motivated. Instead of walking into your quilt cave and thinking, "I need to make this quilt or those placemats," you say, "Today, I'm going to cut the squares for that baby quilt and if there's time, I'll piece the binding for the placemats." It's less overwhelming to think of just one of the steps than worrying about the entire thing.