Dwight D Eisenhower was the Supreme Commander of the Allied Expeditionary Forces in Europe in World War II and then later also served as 34th President of United States.
Being a Five Star General and the most important person on the planet he faced innumerable tough decisions, and thus he developed a very elegant and simple method of decision making.
Essentially, it is all about deciding between a matrix of, what is urgent and what is important.
Urgent and important (tasks you will do immediately)
Important, but not urgent (tasks you will schedule to do later)
Urgent, but not important (tasks you will delegate to someone else)
Neither urgent nor important (tasks that you will eliminate)
“What is important is seldom urgent and what is urgent is seldom important.”
– Dwight Eisenhower