Messiness is a personality trait, not a mental illness. However, it can be a sign of physical or mental health issues including depression and anxiety.
The first step to cleaning a messy house is to decide where to start. This can be a big challenge and one of the toughest roadblocks to overcome.
The simplest thing to start with is obvious trash. It’s easy to identify, and getting rid of it doesn’t normally cause any emotional reactions, so it’s a great task to start with.