Habits are something that is automatic after we have done consciously for a period of time eg, a few weeks to months.
Habits are often labelled as “hard ingrained”. Why is that so? Because when something done over a period of time, it consolidates inside the subconscious mind and is ready to surface to our conscious mind at any time.
Upon consolidation, it becomes hard. It is harder to break it away after that.
Imagine a small lump of sticky substances. Each action produces a few such substances, They are initially separate from one another. Through time, they begin to attract to one another and stick like SUPER GLUE. The more actions we take doing a particular thing, the more substances are produced. And the substances that are in set pieces stick to form one big mass.
This explains why when it comes to breaking habits, most people face difficulties.