We all want to have fun, we want to enjoy. We want to feel an emotional high. Fun is about pleasure - it could be physical or intellectual or even in our feelings. Fun is subjective. It can't be defined. It's different for different people. It's different for the same people at different times.
Fun is to go on a vacation. Fun is to go partying. Fun is work. Fun is romance. Fun is energy. Fun is meditation. Fun is prayer. Fun is success. Fun is helping someone. Fun is all of these to many and more.
In simple terms, when you feel happiness and joy inside of you, that is fun. The path to that happiness could be different. But the final destination is happiness. The road is fun. You can take different paths, but they are intended to lead to the same goal, same end result, same destination.
Fun is a feeling. It's greatest presence is always in the mind. Even when the body is having some adventure or some fun, that feeling is enjoyed in the mind. All enjoyments are in reality only in the mind. Physical and sensual enjoyments have been so created by nature that they are short and fleeting. In this is a sign from our Creator, that everything can be enjoyed, and everything is legal, but the eternal enlightenment is intellectual based. That is what lasts. And when you feel the fun for long periods of time, you are on the path to an awakening, where your intellectual and spiritual senses have been heightened and you can reside in the cozy comfort of their depth.