This question has some overlap with the questions on attention, executive function, and ADHD: but essentially our opinion at the clinic is that a child will almost never be ‘lazy’ as a conscious choice that they feel is beneficial to them. Usually, nobody is more aware than the child (or more upset) when it comes to a failure to complete tasks, a tendency to make mistakes, difficulty getting started with things, and problems carrying out instructions.
Rather than ‘labelling’ the child as lazy (which implies a choice or negative personality characteristic), it is often more helpful to consider whether there is an issue with attention or Executive Function. Similarly, a child will rarely choose to be poorly behaved when they have the emotional and social skills required to behave otherwise: again they will usually be just as aware as others of the negative effects that this brings but they may need psychological intervention to learn the skills they need to respond differently.
Lastly, a child may be viewed as ‘unmotivated’ because they do not know how to get started with activities, they suffer from low energy, they have problems with their mood, or they worry that they will under-perform in things so they choose not to engage in order to avoid failure. Again, understanding the underlying reasons can help us move forward in a way that may not have been considered yet.