It is often hard for people to be convenient in new situations. There might be a lot of reasons for this effect, but I believe the mind structure is the most important reason.
Psychologists say that human mind is designed somehow that gets used to one significant situation. As a result, when a change comes along, it is not an easy step for a human mind to adopt to that circumstance. Therefore, mind tries to stay in the previous state and not to adopt to the new condition. However, it is not something unchangeable. For instance, many academic studies have shown that brain structure can be modified by practice and become more flexible. Furthermore, not all human minds have the same structure. It means that some people are generally more flexible than others.
One solution to making people more flexible and easy to adopt is maintaining knowledge about brain attitude and showing them the knowledge. By doing this, we can find out more about the actual reasons behind inflexibility. Furthermore, when we show people those reasons, they will be more enthusiastic to try new ways for fixing this problem.
Another measure is designing useful games and practices which can create or amplify flexibility in people, because it is practical experience that can make a difference in mind activity. For example, playing some sports that they have not played is one of those practices.
To conclude, we should realize that the biggest obstacle against flexibility is mind and we can overcome it by special and ideal practices.