For me, fun is a cold beer with friends, playing high school football, wrestling live nude women, playing Stratomatic Baseball, old table hockey, running a 5K on the edge of madness, climbing a water tower, pranking a rival high school, riding a GPz550 on a curvy road, almost anything involving a frisbee, along with a myriad of other things I've done that that I knew I couldn't or can't do forever.

I really don't consider cycling fun. It is simply an excellent thing to do.

I put on the shorts and the shoes so I can enjoy my ride.
Most of you have seen this bike before, but the OP asked.

My favorite rides are long solo rides, in the drops. I can think, feel, and move across the planet.
I consider it contentment, enjoyable, and more so on this than any other bike:


There is, however, a potential rival to this bike in the works, similar in many ways, and if a success, will produce the same feeling.