Are you familiar with the story of the professor with the jar of rocks, pebbles and sand?

If not, this is how it goes:

A philosophy professor once stood up before his class with a large empty mason jar. He filled the jar to the top with big rocks and asked his students if the jar was full.

The students said that yes, the jar was indeed full.

He then added small pebbles to the jar, and gave the jar a bit of a shake so the pebbles could disperse themselves among the larger rocks. Then he asked again, “Is the jar full now?”

The students agreed that the jar was still full.

The professor then poured sand into the jar to fill up any remaining empty space. The students then agreed that the jar was completely full.

Now in the original story, the jar is representing everything that is in one’s life. The rocks are the most important projects and things you have going on (spending time with family), the pebbles are things that matter but you can live without (work, hobbies), and the sand represents the filler things in your life (like watching tv).

The point of the story is that if you start with putting sand in the jar (the unimportant stuff), you won’t have space for the rocks or pebbles (the things that matter).

I like this analogy when it comes to task and time management, but I use it in a slightly different way.

To start with, I separate and categorise my tasks according to the mental state required for me to do them.

My main categories are

• Focus/Deep Work. Things that need my best mental clarity and energy
• General. Most of the tasks go here
• Simple. Things I can do even when I’m tired, have brain fog, or not feeling very productive
• Process. The admin stuff, often these are time sensitive, but also not too time consuming
• Communication. Often batched together with Process tasks
• Home. Chores, “non-work”
• Errands. What it says

My Process and Communication tasks get a daily regular time slot. A good time is before or after lunch.

My Simple list is not big, but it’s useful to have things that you can do whatever your mental state is and still know that you are moving the needle forward.

The General tasks is the biggest list, and I try to break them down so they are small enough to fit in a 20-30 min slot or even smaller.

Sometimes you hear the advice to always make a time estimate on your tasks. So your task manager would have labels with “15min”, “30min”, “1h”, “2h” etc. And you would then choose tasks based on the time you have available at that moment.

I actually don’t think it’s a great idea. For starters, most people are really crap at estimating stuff (myself included).

But time is a really interesting thing. It stretches and speeds up and behaves in all kind of non-static ways.

If I’m in a good mental state, something might take half the time I thought it would because I get into the flow.

On the other hand, a task that would take 20 minutes normally can take twice as long or more if I’m sluggish or get interrupted. We also have Parkinson’s law – that work expands as to fill the time available for it.

I only use a time estimate for things I really really know are quick. Most often they also belong to the Simple category, but not always. This is so I easily can find something useful to do if I get a short break somewhere but don’t have time to start something bigger.

For the most part, I prefer to use my mental state as filter towards what I should be tackling next.

So how does this fit into the story of our philosophy professor?

Well in this scenario, the Deep Work are your rocks, the General tasks are your pebbles and the Simple, Process and the rest of the categories are your sand that fit around everything else.

Perhaps you could get two good deep work sessions in one day. That’s the time of day you feel your best, have the most mental clarity, and energy to tackle the big hard things. Probably it’s only one per day – rarely you’d get three.

This means you get to pick ONE item from the Deep work list to tackle per day, and you make sure you do that during your peak mental time. The rest of the day is filled with General or lesser tasks.

You will still need to be focused to do them, and you can use techniques like the pomodoro or whatever you like. The important thing is to not waste your best mental state on a task you can do anytime else.

Time is not of equal value. A half hour during your commute is not the same as a half hour at a calm workspace, a half hour meeting, or a half hour having a conversation with a friend. Time is not fungible.

You want to protect that mental prime time, whenever it occurs for you. For many people this is during the first working hours of the day, for others it’s during the afternoon that they have their best thinking.

If you’re in a situation where others can see your calendar, or book time in it, then adding a time slot on your calendar for that Deep Work can be a good idea.

You’re making an appointment with yourself in order to create an optimal situation for creativity and focus.

I really think everyone would benefit from becoming more aware of and utilise the best mental state for each kind of task.

When do you produce your most optimal work? What are your Big Rocks in life that you want to reserve for those times?