So the state when you are filled with memories of some person whom you still admire or love, although you've lost contact with him or her long ago may be very good as those memories me lead you to great deeds, supply you with power enough to reach very valuable milestones. Though especially today this state may also be hazardous to itself and to your good memories. There are two key reasons standing behind that hazard.
First is the volatility of people's mind and it is most strong in case of young people. People sometimes change and sometimes they do change dramatically. They also develop themselves and usually you can't say where such a development would bring someone in several years. This reason is objective, thus you can hardly do anything about it.
Public access to lots of information nowadays is the second reason. I mean social networks, blogs, twitter etc - the means to easily share every event of your life, every thought and every image as well as the means to easily access. That's one side of this reason - the second one is your eagerness to search for every bit of information on the person you remember, to somehow bring that person from the past closer to the present.
Combining both mentioned reasons one can easily acknowledge the hazard I've mentioned: looking for a person you admired or loved you may come across someone strange - looking for a lost princess you may face a wicked witch. Moreover the truth is that most likely the outcome of an attempt to fetch someone from the past, to feed the memories will be disappointment. That may hurt hardly. That may steal the so important power.
In most cases we'd better dominate our eagerness to ressurect someone who belongs to our past - not the present. Generally we'd better keep our memories in their domain and that domain is memory - the only place for heroes, dreams and hopes, the only place where we can defend ourselves easily untill we are insane. We'd better keep our memories in the past.