Procastination is created by anxiety emotion, if you want to get deeper it is easily explained in this animated movie:
https://archive.org/details/understandingstressesandstrains
Anxiety makes impossible for you to concentrate as it makes your attention to focus on the thread, like an herbivorous animal will stop eating for focusing on the lion.
It is an emotional block equivalent to pushing the brakes while the accelerator pedal. A car that could go to 200, will only go to 10. If you push harder, you break the car. If you know what procastination is,and know how not to block, you can at 200, and enjoy it!!
Anxiety is extremely useful for humans, this baby has none of it. Without the glass wall it will be a good idea that parents have it. https://www.youtube.com/watch?v=KSlrDi9So9w
Nowadays, the more relevant cause of anxiety is other humans, as we have exterminated most of the other predators, in circumstances like war. E.g Recently in Syria, you(or your family members) could die every single day, beheaded after being raped.
It in interesting that in the modern world, in peace, when most problems are not death threats, we increase the sensibility of anxiety making abstract things like not entering University, losing a job or a partner or just being humiliated while giving a speech or rejection, as "live threatening", causing procastination.