I agree with Photomom wholeheartedly! Hopefully by adding a different “dimension” to both swimming and violin, you can reinvigorate your passions for them!
Photomom was reading my mind as well!!! Take something that you enjoy, and expand it. There are lots of opportunities for jr. special olympics - type mentoring & organizing. See what’s available near you. Music in nursing homes as well. You could come up with your own plan & work on it over the summer. I’m sure that you’d get a lot out of it, and it may lead you down a path that you hadn’t considered before, while still drawing on your years of experience.