There is nothing more comfortable than the comfort of our habits. It's not for nothing that they are habits.
We are intelligent by design and part of this intelligence is that we conserve energy like no other beings on earth. Our brain is always looking for short cuts in order to work efficiently. When we learn something, for example how to parallel park, we figure out the moves it takes to get the four wheels perfectly and quickly parked so that each time we parallel park, we don't have to figure out how to do it like it was the first time, again and again. The more we parallel park, the deeper the imprint until one day, parallel parking is as familiar to us as breathing. And so it is with all our habits--the-good, flossing our teeth every day, several times a day, the bad, procrastinating on working out, eating healthy, writing that novel or the ugly and the bad, staying in shitty relationships or having self defeating thoughts etc.
We all have habits that one day were were meaningful but today no longer serve our continued growth.
If you want to purify your life of habits that keep you from growing, feeling healthy, or just keep you from achieving greatness, you need to know about the habit loop. Charles Duhigg, author of one of the most wonderful books I read this year, The Power of Habit: Why we do the things we do in Life and Business" writes insightfully about habits, why we have them and how to break them. It starts with the habit loop:
Cue: The urge, time, location. This is the trigger to your habit.
Routine: What you do almost subconsciously, your habit in motion.
Reward: The things you want, what drives your habit
As Duhigg notes, studies have shown that if you can diagnose your habit, you can change it in any way you want.