If it’s trying to get tasks done at work, then you have to make sure that you don’t needlessly add anyone else’s work on top of your own. It’s okay to agree to assist with a project or favor if it’s not inconvenient or if it’s relevant to your current task. Otherwise, being an overachiever and a yes man might just land you more work than you handle at once.
If it’s over committing to achieving personal tasks then be realistic with your timeline. Do you have the time to spare for ten tasks or five? The priority of tasks is important as well. What are the things you need to do versus the things you want to do? Once you get the necessities out of the way, you see how much time you can actually spare with less important matters. That’s when you decide to choose all the things that can pushed off for later.
If there isn’t a midnight deadline, most over-commitments can be pushed to the next day or even a later date. I’m sure there are plenty of important things that need to be done but it’s also important to realize there’s only so much time in a day.