This is emotion vs. objectivity. I you don't wait, you will continue to be emotional, and will have difficulty separating emotion from objectivity. It's facts vs. feelings. Objectivity is required to serve goal-directed behavior. Perspicacity is the kindling of motivation.
Motivation is an emotion.
The normal attitude with an unpleasant task is that you 'stick with it', as there is a reward at the end. In ADD, the reward must be in the task itself, not after it. Most children can kindle motivation, the ADD child has to find it in what he is doing at the time - he has trouble kindling motivation to do an unpleasant task. Reflection Humans can turn language on themselves. We call it reflection, and its the bedrock of self-control.