Why do we find things fun? One may cause to argue that Fun activities are solely based off psychological and physical identification with certain activities, but surely there is a deeper analysis on why we find things fun. 

Furthermore, what is the relationship of personal experience to what an individual finds fun. Some argue that what we find fun is solely defined by personal experiences, but what about activities that many individuals find fun- regardless of personal experiences.
I would argue that a positive emotional experience is something that evolved for conscious organisms in order for consciousness to function in a way that supports survival and reproduction (thus, sex and eating are pleasurable experiences).

Once having this system, an organism can then find other ways to trigger it that may not lead to better survival or reproduction, but still don't compromise survival and reproduction.  Often, this may be through human invention.  For example, our love of sugar evolved in a world where sugar indicated health (high energy foods that help you survive).  Now, we're able to produce the sugar by itself with technology; it no longer occurs only in the context of nutritional food.

Thus, humans are able to exploit their reward systems and "fun" need not pertain to healthy activities, but may have roots in the evolutionary purpose of pleasure.