We can use the power of mindfulness and self-awareness to help them reframe their negative thoughts into something more positive and helpful.
For example: Your child might start saying negative things about themselves and say they feel like they are "stupid" because they can't do their maths homework.
You can guide them to challenge this thought by asking things like:
"Is this true? What evidence do we have?"
"What makes you think you're stupid?"
"Is that mindset helpful for you to do your maths?"
You can help them reframe the thought to something more helpful, like:
"Maths is a subject you can improve on with practice."
"Tackle a section at a time and ask for help if needed."
This way, they will learn to notice and correct their mindset to help them solve their problems.