People that have a good vision of the end of a task are less likely to deviate from that path until they are finished.
In there own minds they have a clear plan of what they need to do to complete the task and a good feel of how much longer It is going to take. This motivates them to get the task done.
We are all capable of working at a high level of efficiency for short periods but it is hard to sustain over long periods.
If you can read a page of text in 1 minute it is unlikely that you will complete 60 pages in 1 hour as this requires sustained concentration.
However, those persons that are able to get things ‘done’ usually have a good ability to concentrate on the matter in hand, despite the distractions that will occur.
"Nothing is done while something remains to be done.
To finish is the mark of the master."
(Henri Frederic Amiel)
Due to the above it is unrealistic for senior managers to expect people to perform at their peak for sustained periods.
It is much better to plan your number one priority task when you perform at your peak. This is different from person to but tends to be in the morning for most people.
As with all Time Management activities the ability to get back on track when distracted is a good trait.
As usual set your self realistic deadlines and give your self a reward when you achieve them.
If you are distracted try to tidy up any loose ends of the task before being torn away.
Try to think of possible issues and plan to overcome them. Keep focussed.