How I started is in the link. I think I've had a lot of different things motivate me at different times over the years, some of them constant and some of them specific to certain times in my life.

For many years, one of my big sources of motivation was the way I was rejected by multiple teachers before I started: I was told repeatedly that I was too old (as a teenager!) to learn a string instrument, and that it was almost impossible for someone starting at that age. I wanted to prove that I still could do it. At the same time, I was under the impression one had to already play at an advanced level to take lessons as an adult, so I was trying to get good enough to be accepted for lessons -- I only realized that I didn't have to be an advanced player to take lessons as an adult when I found myself playing in auditioned orchestras alongside full-time music teachers. That’s no longer a main source of motivation because I no longer feel the need to prove anything, but I do sometimes feel responsible for representing late starters in my orchestra, because for years I was the only one, and right now it’s still just myself and a cellist who started at 26.

One of the constant sources of motivation is the music I want to play. I have a long list of pieces I want to play at some point in my life, both solo and in ensembles. Now that I'm a fairly experienced orchestral musician, I've crossed a lot of orchestral pieces off that list, but there's still a lot more left. One thing that has changed a bit is that playing the most famous masterpieces is no longer a novelty; now I sometimes have my mind on finishing entire categories of pieces. (For example: I’m now looking at completing composers’ entire symphony cycles. I’ve already played all nine of Beethoven’s symphonies, after next June’s concert I’ll have played all four of Schumann’s, and I’ve played three of Brahms’s four.) I’m also very interested in playing lesser-known pieces that I like, and introducing other people to underrated music that didn’t necessarily come from the biggest names. So I love that my orchestra plays lesser-known composers on a regular basis, and that I’m playing chamber music with people who are open to going off the beaten path.

The other constant is that playing music with other people is incredibly satisfying, whether it’s in an orchestra, a small chamber ensemble, or even a duet. There’s the connection with other musicians; I’ve made a lot of friends through musical ensembles, and even found instant community through impromptu chamber music sessions when I’ve traveled with my viola. In the actual playing, some of the most fun moments are the ones where something really intricate comes together almost telepathically.

And of course, even if there’s no audience, there’s something zen about the act of playing. (Not that I ever lack an audience... my cat is the toughest of all music critics!)