Tell the truth: Do you answer email during conference calls (and sometimes even during calls with one other person)? Do you bring your laptop to meetings and then pretend you’re taking notes while you surf the net? Do you eat lunch at your desk? Do you make calls while you’re driving, and even send the occasional text, even though you know you shouldn’t?

The biggest cost — assuming you don’t crash — is to your productivity. In part, that’s a simple consequence of splitting your attention, so that you’re partially engaged in multiple activities but rarely fully engaged in any one. In part, it’s because when you switch away from a primary task to do something else, you’re increasing the time it takes to finish that task by an average of 25 per cent.

But most insidiously, it’s because if you’re always doing something, you’re relentlessly burning down your available reservoir of energy over the course of every day, so you have less available with every passing hour.

via The Magic of Doing One Thing at a Time – Tony Schwartz – Harvard Business Review.