In my experiment, 92% of those with seven or more tasks answered “No” to the question “Can you do all of them today?” No matter how long the task list is, what you can do today is limited. First of all, let’s pick up only what you really have to do today. Once you finish doing them, you get a sense of accomplishment that you did all the things to do today. Using the remaining time, you can organize other tasks and make a list of tasks to do tomorrow. Let’s gradually improve.
If the things you have to do today are more than you can do today, what you should do is not to do your best at those tasks. You need to change the delivery date, to change the specification or to stop doing it.
see also (Column) Emergency decomposition theory