Did you know that the maximum amount of time a person can focus intently on a task is 90 minutes? Any longer and your sales productivity starts to spiral downhill, your mind wanders and you lose your edge.
So then you start working on things that are easy to do, but not very important in the overall scheme of things.
It's time to get up and move. Go get some coffee. Take a walk outside. Have a chat with a colleague. Call a friend on the phone. Do some stretching. And, if you work at home, consider doing the laundry or something else that's totally mindless.