If you want to run 10 kilometres, then running 5 kilometres one way is pre-commitment. Because, the only way to come back home is to run the 5 kilometres back in the direction you went out in, totalling a ten. 

Running five 1 kilometre loops, on the other hand, is not pre-commitment. Because, you can stop and decide to quit and go back home at the end of any of the one kilometre loops. 

We want to take decision-making control away from the version of us that is most likely to decide to quit or not go through with something.

We don't want the version of us that has just woken up to an alarm early in the morning, whether to work out or not. 

We don't want the version of us that is hungry and craving dessert, whether to eat healthy or not.

We don't want the version of us that is distracted by the notifications on our phone, whether to push through for some more time in finishing that draft or presentation. 

We want the versions of ourselves that are most likely to decide in our long term favour to make these decisions. 

We want pre-commitment wherever possible. 

Inspiration: Chris Guillebeau