First time I read about this book I was so impressed

When you create a product strategy for the first time, for instance, you are likely to make plenty of mistakes. You may not use the right research and validation techniques; your target group may be too big and heterogenous; the value proposition may not be concise and compelling; the standout features of your product may not be terribly exciting; and the business goals may be unmeasurable. But that’s OK—as long as you are able to recognise that you made a mistake and you are willing to learn from it.

Origen: Growth Mindset in Product Management | Roman Pichler

A great way to cultivate a growth mindset and open mind is to learn a new skill (or re-learn an old one).
Another way to avoid a fixed mindset is to collaborate with others.
Finally, try to make regular reflection part of your work…