From Huffingtonpost’s current series on productivity in the workplace.
Pick a simple mental task that won’t take more than five minutes; then time yourself to see if you can complete it in the allotted five minutes without breaking away to do something else or start thinking of something else. Gradually increase the time and see how long it takes you to stay focused and on-task for a full 20 minutes. You may be surprised!
Maria Konnokova agrees:
So if you train it, it gets stronger, it gets better. You are able to lift more weight, we have more endurance. And similarly with attention the more you train yourself to uni-task and to only pay attention to one thing at a time, the longer and longer and longer you’re able to maintain your focus.