Writing in Money Magazine, Tyler Cowen offers an insight into one of the major causes of procrastination: we over-estimate the amount of control we have over our day.
So we could do that unwelcome task first thing in the morning but we say we'll do it later. However, as the day goes on there are more interruptions and more demands from others and it becomes more and more difficult to do what we've postponed - so we promise ourselves we'll do it tomorrow. - but not necessarily first thing.
What can we take away from this? I, too, find it tough to tackle the least appealing task first thing but one strategy I've found helpful is to apply the micro-task method to this.
Spend a minimum of five minutes on the hardest or least appealing task first thing. Often going that far makes it easier to finish right then. If not, then give it another five minutes first thing the next day.