There's a story about an individual that had decided to cut his grass on a Saturday morning.  This activity would have normally taken 45 minutes.  At 8:00 John went out to get his lawnmower.  As he pushed the lawnmower onto the front yard he decided he would go into town to buy more gasoline just in case he needed it.  At the gas station he met a friend and got into a lengthy conversation.  The conversation spanned a timeframe that was well after his gas can had been filled and he was able to leave.  His friend then suggested they stop and have a cup of coffee together.  By the time John finally arrived home he had used up an hour and a half of his time.  Just as he was ready to start up his lawnmower his wife called out to him to let him know he had a phone call.   After the phone call it was close to lunch time.  His wife asked him if he would like to have a sandwich.  John then made the decision to have lunch prior to mowing the lawn.  At 1:15 John actually got back out to the lawnmower and started to cut his grass.  A neighbor walking his dog then came by and politely got into a casual conversation with John.  By the time John finally completed cutting his grass it was 4:10.  What could have been a 45 minute focused project turned into a day long project with many interruptions. 

Now I cite this example and ask, "In the work environment do you make a decision to work on a project only to find out that it took longer than it should have, not so much because of the interruptions but because you allowed the interruptions into your space?"