Mindsets are beliefs. Beliefs about intelligence, talents, and personality. People think that intelligence, talents, and personality are inner and fixed qualities. Barbara Oakley says in her book, A mind for numbers: "Reshaping your brain is under your control. The key is patient persistence-working knowledgeable with your brain's strengths and weaknesses." That's what Carol Dweck calls "growth mindset", that is, your skills can be developed through dedication and effort. The message is: you can expand and improve your mind at any age.
Don't miss the following video on this subject. The power of believing that you can improve by Carol Dweck - TED Talks
Carol Dweck researches "growth mindset" - the idea that we can grow our brain's capacity to learn and to solve problems. Subtitles available in 15 languages TED talks.