Years ago when I was first learning to knit, I had a couple of friends who knew how and I was discussing my progress with them. Over the course of the conversation, one of them happened to say, "Oh yes, and knitting is great because you can do so many other things while you're knitting." To myself, I thought, "Uh, OK. Whatever you say." But, I had to resist my desperate urge to wholeheartedly disagree. Surely I listen to music or the radio or I listen to what's on TV with only the occasionaly quick glance up, but to what the hell else could she have possibly been referring? Reading? Sex? At this point, I guess I'll never know.
I find that knitting requires focus and concentration to be done well, regardless of how simple the project. I know it's not brain surgery, but still!