The Teacher is talking about our attachment to the youth of our body. Our vanity. It is a very good talk, given in a retreat in New zealand in 2002. This nun had been a nun for decades. I am not sure how she could upheld her vows for so long. Such a hard ,modest routine of a  disciplined life. 

You can hear this very good (warning: it is religious at times in her teachings so she speaks of the supernatural psychic powers so called of the Buddha) teaching HERE