Based on the free bookboon.com book.

The procrastination is the act of replacing high-priority action with task of lower-priority, or doing something from which one derives enjoyment, and thus putting off important tasks for a later time.

It is also defined as the act of voluntarily delaying an intended course of actions despite expecting to be worse off for the delay. The consequence of this putting off important tasks is a sense of guilt that cause lost of motivation.