The biggest mistake I ever made was deciding to stay in Germany after having spent a year in the country as an exchange student. At the time I thought it was great that the university was free to students and I liked my new friends, which is why I decided to leave my university and transfer as a full time student to Germany. However, I soon realized that it is hard keeping in touch with my old friends and if I could do it over again, I would have stayed where I was. In the end, I would have been happier and have had a lot more fun with my good friends that I left behind.