It's becoming clear that multitasking doesn't work for, well, any of us. Scientific study after scientific study says that our brains aren't really built for doing many acts at once. Instead, when we multitask, we are just picking up one task, dropping it rapidly and picking up another task, etc. It is about as efficient as it sounds.
I actually studied it myself for my book, Our Virtual Shadow: Why We Are Obsessed with Documenting Our Lives Online.
Instead of multitasking, you should be multipurposing.
Many birds, one stone
What item on your to-do list gives you the most bang for your buck? For instance, TED speaker Nilofer Merchant talks about the power of walking and, to take it further, your time outside could be spent having a walking meeting or thinking about your current business strategy. It is about overlaying two priorities rather than juggling them.
Focus on the big picture, not the to-do list
We usually focus on a particular way of doing things. Instead, it's more productive to understand why you are doing something and then smarter, more elegant options start to appear. Multitasking leads to narrow thinking, as in "I have to do this, and I have to do that, and they are separate things." It is much more productive to think about what must get done, then to plan your actions as a whole.
Stop worrying about feeling productive
We multitask because it feels good: We're getting so many things done at once! However, if we really want to be productive, it is best to settle on getting one thing done well - and choosing that one thing to get done well wisely.