Simply put: Work on it for five minutes. lol.
For instance: If you have a sink full of dishes that would take forever to clean, will yourself to wash them for 5 minutes. Even if you don't complete the entire sink full, at least you make a dent.
Now, what usually happens though: Once you get started washing the dishes for 5 minutes, it becomes easier to continue (because your hands are already wet after-all). So, don't be surprised if you end up completing the job (even if it takes longer than the 5 minutes).