The Ivy Lee method has been explained as
- At the end of each work day, write down the six most important things you need to accomplish tomorrow. Do not write down more than six tasks.
- Prioritize those six items in order of their true importance.
- When you arrive tomorrow, concentrate only on the first task. Work until the first task is finished before moving on to the second task.
- Approach the rest of your list in the same fashion. At the end of the day, move any unfinished items to a new list of six tasks for the following day.
- Repeat this process every working day.
James Clear explains this here.
This is similar to the Warren Buffett 25/5 method for longer term planning.
- List the 25 most important things to you.
- Select the top 5.
- Avoid doing anything in the other 20 until you’ve succeeded at the top 5.
Both force you to make hard decisions and focus on what’s really important to you.