Rebooting One's Brain

Once in a while I find myself working on a task that requires infinite effort to complete in my current state of mind. That's to say that no matter how hard I work, it's not hard enough and I serve only to frustrate myself by attempting it further, no matter how much I want to get it done.
In these situations the best thing I can do is walk away. This illustrates one of the reasons it's such a bad idea to leave a task for the last minute. By working on things early there is a lot less stress because there is time to screw up and try again. Numerous other people also recommend walking away from the situation temporarily. Often the answer comes when a calmer state of mind is reached.
Any given task that's impossible to complete in the current state of mind serves to prevent other, completable, tasks from being given attention. On several occasions I have focused on one thing only to become depressed and waste an entire day accomplishing nothing. What does one do when he or she realizes that nothing is being accomplished? Procrastinate! This downward spiral can only be broken by working on something else before the impossible task consumes the worker. Best of all if the impossible task is given a rest soon enough, one's moral doesn't have to suffer through other situations that are otherwise unrelated.