"I'm just trying to capture something so that I don't have to keep it in my head." Exactly. I've been carrying a pocket notebook on me (usually in my pocket, in fact) for almost three years and it has been transformative. I call mine "context" and the most important thing about it is that it is temporary - context is the capture point, not the action point - but it is out of my head. Having that process of transferring my notes into the places where I am going to actually do the work gives my subconscious a signal that this is a place that it is safe to put my thoughts because I will come back to them.