But of course there is another way to get more stuff done with less stress! The "6 most important things I must do tomorrow" is an excellent tool.
The idea is so simple it's almost ridiculous, still this is what nearly doubled the efficiency of a large steel corporation back in the early 1900s, and also earned a man 25.000 dollars in twenty minutes (in today's money that's approximately 500.000 dollars - you can read the whole story here.)
This is how to use this tool: Every night before you go to bed, write on a piece of paper - exactly - "The six most important things I must do tomorrow"... and you write down the things as they come to you. Not the 36 most important things, not the umpteen things I ought to do, but the six most important things I must do tomorrow. Then you number them according to priority, from most important number one, down to least important.
Each thing should be a complete task, but a doable activity, like paying your bills, answering an important email, scheduling an appointment, planning a meeting etc.
When you start your day, you start doing the first thing on your list, and continue downwards. A day when all six get done is a good day, and you can pat yourself on the back and be very proud. When you don't get them all finished, they may go on tomorrow's list, or you may need to break each activity into smaller tasks. If you get all your things done before lunch, that's a great day, and you can relax in knowing that you've got it covered.
Do this every day for two weeks, and you will be amazed at how you manage to get on top of things and how much more efficient you are.