Bob Walsh has shared a productivity method he uses for Getting Things Done which involves setting aside specific time each day for the big task. It’s called Butterfly Stroke Productivity. This is done in the morning as you review what is required. The approach manages both priorities and capacity, something Getting Things Done advocates strongly.
Here’s how it works. As you plan each day’s work, focus on the 2 or 3 things which you’re going to have to really work at for an hour or two each to get done. These should be things you want to reserve your best efforts for because they will make the most difference in your life. Now, make a 60-120 minute appointment for each. You can make it an Outlook Appointment, a Task Appointment in the program I sell or an entry in your daytimer. Leave time between these task appointments so you can come up for air, re-orientate and deal with other, less important stuff.
The detail of how this works is important and so I suggest you take the time to read the original post for the full run-down. I like the idea because I often find that I get small things done at the expense of getting big things done. It is productivity but can hide the importance of the items that need to be worked on. Yesterday I did manage to find some time for an important item and managed to knock it over in thirty minutes rather than the two hours I had expected. Unfortunately it was a week later than I wanted to do it.