In my opinion, the hardest part to adapt to a new culture is that you are familiar with the culture in your home country. Such as when you study abroad, you extreme homesickness. Also, you will desire to avoid social settings that seem threatening or unpleasant, physical complaints and sleep disturbances and depression, and feelings of helplessness difficulty with coursework and concentration. Besides,  you will lose of your sense of humor and boredom or fatigue. In particular, you will hostile culture and have a culture shock.