The only downside to my lone rantings is that I sometimes enjoy the conversation so much that I forget bits of it. For example, I've recently been throwing around the elements of the end of my novel which presents the final confrontation. It's an exciting, fast-paced series of events that I've rolled out in my imagination like scenes in a film.
Enter protagonist who is immediately accosted by antagonist and his helpers.
Switch to protagonist's friends who are finding another way into the building.
Switch back to the captured protagonist who...
It goes on and on and when I initially began to run this film through my mind, I forgot a couple of details. I was forced to retrace my thought process back but then I lost some of the later details and had to go forward through the train of thought. I should know better because I've already learnt the lesson that it's fine to get carried away in this brainstorming of ideas, after all it's that enthusiastic wandering that makes my writing so organic, but that I must also make notes, be they scribbled on a pad, typed on the computer or added to the note function on my mobile phone.
Always carry some way of recording your thoughts, even if it's only a pen and a screwed-up receipt. Make sure that when the muse bashes you on the head with the speaking stick, you can record the resulting inspiration. If you only have space for one word or a phrase, that's fine. Just ensure that you make a note.
I have some work mapped out on my novel to get back to. I have three men in a dark apartment and a robot. At the moment, I'm throwing around the ideas of where they find the robot and how it reacts. Is it violent? Is it on charge? I haven't figured that one out yet but before I get too carried away, I need to find a pen.