The thing that triggered my "comeback" (it still feels pretentious to call it that) was picking up a horn after two years of singing lessons and a lot a time spent working on breathing (and all the mind games that singers use to get the best out of their instrument). I'd had a good trumpet teacher and learnt sound breathing and breath control all those years back. There is however fantastic synergy between playing trumpet and singing. I also noticed that playing trumpet before singing was like having an amazingly effective vocal warm-up. Everything feels so freed and relaxed.
Obviously as a late starter to singing, and not being gifted with naturally great pipes, opera is not on the menu for me. It's great to hear that the cross-over benefits work for a professional singer too.