Mental models are the representations in your head of how you view the world. It contains the processes of how you believe the world works and acts. Your mental model answers the question of why, regarding many things that happen.
What I have been thinking lately is that if things that happen to you continually continue to surprise you, catch you of guard or even shock you then you might be in need of a mental model update. Life should be a process of continual growth. If things in life leave you surprised then it is your duty to actively start to consider adjusting your mental model to a newer one.
For example, if you believe that investing in the stock market successfully is pure luck and basically for gamblers. You need to change you mental model of the stock market. Many people who have made tons of money in the stock market have merely gambled but that does not mean that gambling is the correct way. There is a smart, safe and correct way to invest in stocks. Those techniques can be learned by studying the teachings of Benjamin Graham and Warren Buffett.
Changing your mental model is as simple as educating yourself on the matter at hand.