When he was little, my husband’s mom used to set a 15-minute timer for dreaded tasks like cleaning. Her mantra was, “You can do just about anything for 15 minutes.” (I’ve since learned that this mantra came from FlyLady, whom my mother-in-law follows faithfully.)
If you have a task that seems daunting and overwhelming or one that is just going to take a lot of time, start today by setting a timer for 15 minutes. Do what you can; then don’t worry about it again until tomorrow.
You’ll find that, if you stick to handling the task every day for 15 minutes, you’ll eventually finish it–and then you can move on to another.