But I really don't will have a musical instrument with me, and inspiration can strike at any moment. Maybe in a vehicle and so on public transport. I'll have lyrics and/or melodies make themselves known for me, and I'll provide the burning desire to do them, but I won't because I really don't have a working system with me.
I enjoy finishing song ideas right away, and sometimes it means dropping everything. Capable of immediately flesh out a concept is frustrating to me.