Not motivated to take on / finish a task

Before You Begin
Pause and breathe. Even if this shouldn't be happening... accept that it is and embrace it with composure and calmness.
Calmness is the only way forward because without calm, there is no possibility for receptiveness and connection. Your child won't give to you any more than they see from you.
Never forget that a strong connection is fundamental, as there will be no correction in them if there is no connection with you.
The Core Problem
Not understanding the value or relevance of completing the task.
What Will Make It Worse
Pressuring the child or using external rewards as the sole motivation will hinder the development of intrinsic motivation.
What The Child Needs
1. To understand their gain from completion: Help the child understand the purpose and relevance of the task in relation to them. Help them see the self-serving benefit they will get from completing the task.
2. To break the task into smaller steps: Help the child break down a large task into smaller, manageable steps to reduce feeling overwhelmed.
3. Autonomy: Empower the child with some autonomy in how they approach the task, allowing them to enjoy taking ownership and getting decision making experience.
4. Positive reinforcement: Offer positivity and recognition when the child shows effort, perseverance, and improvement in completing tasks.
How To Have The Conversation With Your Child
Begin the conversation calmly, expressing that you have noticed that they are having trouble finishing, or starting, the specific task.
Continue with support, highlighting things they have worked through to completion in the past, and making the connection that this task at the moment is no different.
Work through the list of what they need in a tone that makes them feel like you are helping them to benefit from doing the task.
Ideally your child comes away from the conversation believing that the task is well within their ability and that there is something inherent to be gained by getting it done.