One quilter told me that she never went to bed until she spent 15 minutes quilting. I took her advice to quilt 15 minutes a day, but not before bed! (yea, I am usually cross-eyed by that time)
I always keep a packed travel baggie with a hand-sewing project for those long sitting/waiting times and traveling.
I also keep ongoing projects in various stages. Sometimes I feel like assembling blocks, sometimes quilting or cutting.