I love running, absolutely love it. In the past, I used to run at least 10 times a week and do a 4hr+ run in the beautiful mountains near my home about once a month. I enjoyed the nature, I felt good, and it did wonderful things both for my body and mind. It's amazing how easy everything feels when you have a resting pulse of 50!
On the other hand, I don't run anymore and unfortunately running fitness can be built or lost very quickly. After a few months of inactivity it really is mostly gone. Looking back on it now, it's very difficult not to feel a little bit guilty about all the hours I spent on running trails. I too, would prefer to have been building lasting skills such as learning a musical instrument or dancing.
The one exception is the times I went on long runs with my old roommate. That was worth it in every way since we often had great conversations and got several hours worth of running outdoors as a bonus!
My problem is that I don't, basically. I hate the feeling of being sweaty, the shortness of breath, the constricting feeling in my throat, the thirst, etc.
But most of all I hate that if I spend the time doing that and the stop, six months later I will be back to square one. If I spend the time learning a new skill, reading a book or even watching a movie then six months later I would still have the skill or be able to talk about the book or the movie.