I guess that creative outlets change from time to time. For years and years I put a great deal of creative energy into composition. I found a crazy fulfillment from writing. It was the first thing I wanted to do when I woke up in the morning, and I would put off other tasks in order to work out ideas. I even enjoyed working out ideas and then discarding the product. I did put time and energy into trying to become a better violist and a better interpretive musician, but not having to attend to the physical production notes on an instrument in real time is a great "ladder of escape." When you write a piece of music it is usually another person's responsibility to make it sound good. It is also another person's responsibility to determine what it "means."
Lately I have been getting intense enjoyment from playing old notes and old phrases written by people I probably never would have met had I been alive when they were alive. I really get a kick out of figuring out how I want phrases to "go." It is as if some switch has been turned. I still have the skill to write, but lately I prefer to devote my time to listening more carefully and becoming a better player. The music running through my head these days is mainly music written by other people (sometimes it is music that I am arranging, but more often it is music I am practicing). And I feel oddly at peace.
I sometimes ask myself if I am still a composer when I am not in the process of writing something. I also wonder if I am less of a composer because I tend to neglect the business-related things that composers have to do in order to have my music played. The answers to these questions don't matter at all.
It is simply a pleasure and an honor to be able to be a full participant in musical life, even when it is physically exhausting. I can't think of a better way to spend my days.