In The 7 Habits of Highly Effective People Stephen Covey talks about the anecdote of the professor who has rocks, pebbles, and sand and has his students put all of them into a jar. The only way it all fits is if they put in the big rocks first, then the pebbles to fit in between the rocks, then the sand to fit into the remaining cracks. This is the argument to Put First Things First - but the issue is that there are only enough big rocks to fit into the jar. In reality there’s an infinite amount of “big rocks” in this metaphor - the things that you could and perhaps feel like you should be spending your time and attention on. You have to choose which big rocks to put in, and that means you’ll necessarily be leaving out the vast majority of large rocks that could be in there.