When I don't have an actual sewing project with me to work on, I always have my graph paper, colored pencils and thinking cap so I can sketch and design ideas for projects for the future. These are much more practical for some places one must be/go and always easy to stick in a bag or suitcase. I also do this in the evenings and other times when I can't sew.
I always have projects at home, I just can't always work on them. The mind is willing but the body doesn't always cooperate. LOL