The power of less is a book by Leo Babauta. This book is full of good stuff.
Chapter 2 is about "The art of setting limits".
Chapter main idea :
[h4]Setting limits is mandatory and is a iterative process[/h4] Our time and space is limited, so we need to focus on limited items.
If you just take all comes to you, you'll not be able to achieve it. you'll have to many actions to do, to many phone call to give, and so on...
If you live without limits, it weaknens you in many ways, it dilutes your power and effectivness.
You can set limits on emails, daily tasks, the amount of time spent on the phone, the number of projects you have on your plate, ...
To set the limits, you have to find the good number of items that fit to you.
For this you'll have to analyse your habit and define a limit, test it for a week, adjust, and adjust again.
Here's a quote from the book :
[blockquote_with_author author="Leo Babauta"]
1. Analyze your current usage levels (how many times do you do something a day ?) and pick a lower limit based on what you think would be ideal 2. Test it out for about a week, and then analyze whether that's working for you. 3. If it doesn't work, adjust to a new level you think might work better, and test that out for about a week. 4. Continue to adjust until you find the right level and until you make it a habit.
If you want to read the full story, you can buy the paper or kindle version of the book here : Power of Less, The: The Fine Art of Limiting Yourself to the Essential