Your time should be used wisely

Remember who you are and where you are. Students don't like, when their teacher begins to tell them about his life, how better it was when he was younger, how better and more patient all students were then, blah-blah-blah. Your student visits your lesson to learn something on the subject, so, don't give him a reason to miss this class next time.
Remember, that time is important for your students as well, so, they would not be happy to waste it for lessons which don't give them anything except personal stories from their teacher's life.