Addiction - finding it easy to change
The conscious side of our brain is very small and pretty simple - we can only hold about 3 or 4 things in there at the same time (unless you have kids, then it's about 7!). Everything else - our memories, our emotions, our morals, our learnt behaviours - are all held in our subconscious. It's a bit like an iceberg - the conscious is the tip you see above the water, the unconscious the huge hidden mass of ice underneath the surface.
When you do something exactly the same way a few times in succession, your subconscious notices and starts to take over for you, in order to release your conscious for other things. Driving is a good example of this - at first you had to really think about every manoeuvre, checking the mirror, indicating, changing gear etc, but now you don't think twice about it, you're on 'autopilot'. But when you decide you want to CHANGE a subconscious behaviour, for example a drug or gambling habit, you may find it difficult because your subconscious still believes it is necessary/helpful in some way.
'Addiction' is not always physical, in fact most of the common addictions are 99% psychological. Any physical 'withdrawal' symptoms felt are often largely psychosomatic as we believe it has to be really difficult to change, which is why hypnosis can be an incredibly successful treatment for pattern-led addiction. Drugs, gambling, alcohol and more can all be treated really easily as long as the desire is there. A therapist cannot make anyone 'want' to do something, but we can help you to find it easier to do something you have decided to do.