My life is filled with useful numbers. Body measurements track my health. Bank statements gauge our finances. Thermometer readings inform the coming day. Even my job as a social scientist has me working with numbers every day.

One number in my life is different from the rest. It terrifies me.  It is a growling Rottweiler in a room full of poodles. It also inspires me.

It is the number of weeks that I have until I die.

Of course, I don’t know the exact number. I may never know until the very end. But I can make an educated guess.

My mother died, and broke our hearts, suddenly and unexpectedly at age 62. She had a massive stroke while sitting in her car at the parking lot of her workplace. My father lived another twenty years until age 82. He died after a long decline in health and functionality. He was in a hospital bed, with my sister in the hallway talking to the nurse.

When will I die? Life expectancy tables say my mid-eighties. So, I have chosen an arbitrary death date of my 85th birthday.

After I picked this date, I calculated the exact number of weeks that I have left. Then I freaked out. We all know that we’re going to die. That’s not news. Social convention is that we don’t think and talk about it unless something dramatic happens. It felt like I shouldn’t be thinking about this number. It was upsetting and agitating.

It was also very valuable. This number reminds me that I have limited days left here on Earth. My theology says that I am not immortal in my current state. My heart, though, doesn’t know this. Deep inside, I cannot conceive of myself not existing in this body in this world.

This infinity assumption gets me into trouble. I act and think as if I have all the time in the world. Today’s troubles propel me forward with a sense of urgency. Dreams, hopes, and goals for the future? They lack urgency, so I put them off. After all, I have plenty of time to get to them, don’t I?

Tracking my remaining weeks makes the long-term urgent. I am 57 years and 3 weeks old. If I die at age 85, that’s only 28 years left. I know what 28 years looks like. In fact, I’ve lived it twice already. It’s not that long. I have been married for 29 years. I remember that wonderful cold, snowy day like it was just yesterday. Will my death feel like it’s just tomorrow?

I use time like I use money. When I think that I have lots of money, I spend it freely—almost carelessly. Why not? I’ve got lots of it. When I think my money is running low, I become more careful. I spend it on what really matters.

Tracking my weeks makes me more careful about how I use my time. Distraction and folly become less appealing. Courage for what matters most becomes more important.

I am not the first person to keep death in mind. This idea shows up in philosophy systemsmeditation practices, and commencement speeches. It’s even in the Bible.

To track my time left, I created a spreadsheet to calculate the number of weeks. Then, I wrote that number in the upper, righthand corner of the whiteboard in my office. I updated it each Saturday morning, reducing it by one.

Weeks are a better unit of measurement for me rather than days, months, or years. I currently have 1,455 left. This is a small enough number that I can comprehend it. It’s big enough that change in it gives me a sense of time passing.

This summer I discovered another way of tracking my time left. It’s called the Life Calendar. It’s a poster that has a little box for every week of life until age 90. There are 52 columns of boxes—one for each week of the year. There are 90 rows of boxes—one for each year. (I covered the bottom five rows—keeping with my age-85 projection). I put my calendar on the side of my office file cabinet so that I see it every morning. I put a magnet on the current week and move it over one box each Saturday morning. At a glance, I can see how much time is behind me and how much time is before me.