You want to know the simple formula for getting things done? Here it is.

**Probability of doing * Probability of completing = Probability of getting things done **

Since there are no guarantees things will be done, the formula is written as probabilities. The first part reflects how likely you are going to start a task and the second what are the odds you will complete that task.

Basically, the formula states if you don’t start AND you don’t complete, you don’t get things done. Well, duh. But before you continue railing on my obviousness, this formula represents something deeper.## Things interact in ways you don’t expect

If you ask someone, “If you have a 95% chance of starting something and a 95% chance of completing it, what are your odds you will get it done?” Hearing 95% is not unusual. The problem is it’s wrong. It’s 90%. Well, you may argue it’s not that big of a difference so who cares? It matters because things are rarely so efficient. If you have a 70% chance of starting something and a 70% chance of completing it, your overall odds drop to 49% not 70%. Or what if you have a 10% chance of completing it, what are your odds now? It’s 7%. It’s lower than either starting or completing percentages. How’s it possible? It’s because getting things done requires you to start AND complete. You need both to happen for success. You can’t complete what you don’t start. And even if you do start but don’t complete, it’s not done. The formula just makes it explicit your odds of getting things done are the PRODUCT of the two probabilities. The two interact with each other. So, it’s NOT the average NOR the lower of the two. Unfortunately, most people don’t think that way. The formula just makes the relationship clear. So, if you’re the type who finishes what they start (say 100%), then you mastered the second part of the formula. But it means little if you never start (10%) for an overall success of 10%. Likewise, if you are good at starting (100%) but bite off more than you can chew (say complete things 50% of the time), then you will be done 50% of the time. So, sizing as well as scheduling both play key roles. Let’s look at the formula one part at a time.## If you don’t schedule, you aren’t going to do it

The probability of doing is another way of asking if you’re going to leave things to random chance. If you don’t have a deadline, then all you have is your initial interest in getting things done. The irony is this is when your motivation is the highest. So, if you’re not going to do it at the beginning, then your motivation just drops over time. This effectively means you won’t do it at all. Say you state you’ll work on something within the next 7 days. Unless you fix those 7 days, it’s constantly moving with you and your odds of starting are always at 1/7 (~ 14%) assuming your motivation stays up. Now imagine if you state you’ll get started by the end of a 5-day work week. At the beginning you have a 20% chance of starting on it. By midweek, you have 3 days left so you’re at a 33% probability of doing it. On deadline day, you can’t procrastinate any more. You either do it or not with a probability of success at 50%. So the value of scheduling or imposing a deadline is it increases the probability of doing- the first part of the formula. And scheduling doesn’t have to mean a particular time or date. It can be any event that happens regularly enough or on a set schedule you can use as a trigger to start things.## Do you complete what you start?

For anyone who’s done big projects, starting doesn’t guarantee completing. Either life interrupts you or your plans don’t go in the direction you wanted. So, what do you do? Ideally, you make enough progress to keep your motivation up. This in turn will allow you to press on regardless of what happens. That’s where the second part of the formula comes in. Completion is making enough progress that you’re ok if you had to stop- “it’s done enough.” So, the probability of completion is inversely proportional to task size. The bigger or more complex the task the smaller the chance you complete it. This is not a reflection on you. It’s just a size thing. Larger tasks take up more time, energy, resources, etc. So, the chances of something going wrong or interruptions are higher, preventing completion. That doesn’t mean you can’t do big tasks. The trick is to break them down into smaller ones so even if you’re interrupted you still made progress. For example, if something takes 2 hours to do, you can choose to do it in two 1-hour segments or one 2-hour stretch. Now, imagine going with the two 1-hour segment and your coworker comes by 50 minutes after you started. They tell you there is some mandatory meeting you need to attend but don’t need to prepare for. Since you have only 10 minutes left, you know the end is near (you’re 83% done). This can motivate you to finish off your first 1-hour task. Now, if you’re doing a 2-hour stretch, you’re less than halfway done (42%). At this point, you might go, “Well, I’m not going to finish so might as well stop and surf the net before the meeting.” For most people, as long it’s a task they don’t hate, the human mind doesn’t like loose ends and wants to finish what it started. Scientists call this the Zeigarnik effect. If the task sizes are small, you have a higher chance of finishing them in the face of any disruptions.## Formula in practice – an example

I wanted to clean my home office desk which I hated doing. I estimated it would take 4 hours to complete (I have a big desk with lots of paperwork). Despite numerous reminders to do it, for 6 months I never found a Saturday or Sunday with 4 hours to spare. I did, however, have small increments of time here and there. But my goal was to clean the entire desk not just part of it since I hated cleaning. I had an all or none mentality and didn’t do anything because there was never enough time. Finally, I got fed up with my cluttered desk. I decided to do something rather than continue whining about it. I figured some progress was better than none. Still, I was not happy I had to stop work on more important things. Cleaning my desk was not on my top 5 priority list but I needed a solution. My experiment was to use one of my break periods from work and spend at most 5 minutes to clean. I picked 5 because I didn’t want to devote any more time to such a “useless” activity. To keep my motivation up, I used the Seinfeld technique of not breaking the chain to track how often I cleaned. Going back to the formula, I knew I took breaks everyday so that probability was high (>90%). Since I limited the activity to 5 minutes, I knew I could complete that task reasonably well (>90%). So, from the math alone I should be doing better than 4/5 (actually 81%) assuming my estimates were right. What amazed me was it worked. In fact, when I looked at my logs, I was completing the 5-minute cleanup almost every day (~ 95%). Sure, it took several weeks and when I added up the time it was 2 hours more than I expected, but the process was painless and it got things done.## Lessons learned

- I finally cleaned my desk. What I waited to do for 6 months I got done over the course of several weeks.
- It took 6 hours instead of 4. Yeah, I could have been more efficient in one shot. But if I had spent 4 hours and not completed, then I would be pissed and less likely to do it again. In hindsight, 6 hours is probably more realistic as humans aren’t great at estimating time duration for tasks.
- Before I had tried divide and conquer where I would clean only parts of my desk. I didn’t like this because I didn’t always finish a section then I would just see what’s left not what was done. This was frustrating. Using time as a constraint, I changed my definition of complete from being a portion of my desk to time. As long as I put in my effort and used up the clock, I made progress and it felt good.
- I also found once I started I spent more than 5 minutes to clean the desk but willingly. Maybe this was procrastination- I don’t know. All I do know was it was weird. Mentally, I knew I was doing “extra” and didn’t have to do this “thankless” task. But knowing I was choosing to spend more time rather than having to do it felt empowering.