Scheduling a power hour is a good solution to tackle those tasks you don't want to do -- but you still have to do them. As an alternative, try swapping your least-loved tasks with a colleague.
The Daily Muse promotes the idea of a "work swap":
Next time you're facing one of the aforementioned situations -- or any other time at work when you're not sure how to (or just don't want to) move forward -- turn to your closest colleague and ask if he or she wants to swap. You send over one of your abysmal tasks or problem items, and your work friend sends one of his or hers; and you both get to work. (Obviously, this works best with someone moderately familiar with your work, like a colleague in the same department or similar role.)
Not only does this clear something from your to-do list and give you peace of mind, it also might mean that someone else comes up with a better solution for the task, which will serve you well in the future.
Our Favourite Way to Get Our Least Favourite Work Done [The Daily Muse]