I have got my medical degree some years ago. Of course, I were taught abundant of knowledge that time. But the most important lesson I learned is responsibility.
In clinical years in colleges, students were allowed to be small part of quite big medical teams. We all often faced with clinical problems which were mainly about what were the diagnosis and how to treat them. I realized that the tasks weren't so easy and they usually required some processes of works. Sometimes we didn't know the answers initially, but after classical delicate processes we eventually found definite answers. After I observed some of my role model professors, I noticed that proper attitude and responsibility play the key role in the processes. We occasionally faced difficult problems, but with responsibility we can solve them in the correct ways.
When I did the clinical practices myself after graduation, this invaluable lesson was very helpful. There are somethings we don't know and the responsibility help us to learn and improve ourselves.