One of the questions I get a lot from my potential adult students goes like this:
“I have no experience/limited experience with music, I've never played the violin/viola/instrument, is it too late for me to learn?”
My answer: It's never too late to learn.
I've had adult students who have become really beautiful players. I admire and respect them, and I'm very proud to have had a hand in teaching them. Some play for themselves, others have gone on to play in community ensembles, church worship, 'jam' bands or ensembles.
There seems to be an idea out there that if you don't begin playing when you're a child that you can't learn to be competent at an instrument. In my experience I've found that sometimes adults may lack the quantity of plasticity and malleability that kids may innately possess. But, I think adults have the advantage in analytical thinking and problem solving skills. Whether you're a child or an adult, the fundamentals of playing don't change, there's simply a subtle difference in the direction by which you learn them.
All that being said, I think there are some qualities that adult students need to possess in order to be successful in learning an instrument.
You must be willing to be vulnerable, in the sense that you must be willing to make (a lot of) mistakes. You must also be willing to make them in front of another adult (me).
This is probably the most crucial trait of successful adult learners. As adults we're very used to being competent. Even when we don't know how to perform a task, we possess the skills to learn how to perform it, typically rapidly and without much practice.
However, playing an instrument is a fabulously complicated skill. As adult musicians, we often understand things intellectually, conceptually, and artistically before we are able to coax our bodies into consistently performing the delicately complex movements that produce the sound we want to hear.
That's why practice is crucial: to you, to me, to every musician that has ever played. Professionals, amateurs, and everyone in between; We are ALL striving towards the sound we hear in our mind's ear. We all practice, we all make mistakes, and we all need to be okay with that process. You'll get there!