Trying to Do Too Much
One common reason that people never get done what they want to get done most is that they are trying to fit too much into a 24-hour period. The solution isn't better time management. If you're like me, no amount of time management will allow you to do it all. The solution is to realize which items on your to-do list that you don't actually have to do.
A quote from Chinese writer and educator Lin Yutang expresses this well:
"Besides the noble art of getting things done, there is a nobler art of leaving things undone... The wisdom of life consists in the elimination of nonessentials."
One of the seven secrets in Stephen Covey's Seven Secrets of Highly Effective People is "First Things First". This concept is so important that he devoted a whole separate book to this one secret. In discussing the problem he notes that there are two dimensions to tasks - urgency and importance - and these are not the same! He suggests categorizing tasks on each of these dimensions:
Important and Urgent - Things that are important to your long terms goals, and also time urgent. You will tend to get these tasks done.
Important but not Urgent - Things are the things that you really care about and really want to do, but somehow never find time to do because they are not time urgent. This is the area of greatest frustration - reading that book you've wanted to read, starting an exercise program, learning a new skill, etc.
Not Important and Urgent - This is the major area that needs trimming, and also the most difficult area to trim. Urgent but unimportant tasks are those that are important to others but not you, things that others are nagging you to do. "Please call me back immediately!" "I need your help with this!"
It can be very difficult to distinguish between urgent tasks that are important and not important. When you read Covey's First Things First it seems very clear, but I found that when I looked at my own to-do list, it wasn't clear at all. It helps a lot to write the personal mission statement that Covey recommends to clarify for yourself what is truly important in your life.
Another reason trimming in this area is difficult is that it generally involves saying no to people, which many find very difficult to do. But if you don't learn to say no to some requests, you will end up with a life that is filled with doing nothing but meeting the demands of others. The demands of others are endless - only you can set limits.
Not Important and Not Urgent - This category is classic time wasters - playing solitaire, watching mindless TV, etc. Stop doing this and, POOF, you have lots more time!
David Allen's Getting Things Done will make you more efficient, but does not address the question of which things are worth doing. Covey's First Things First can help you get a perspective on this. It's a lot easier to get done what you want to get done when your to-do list is shorter!