Life is about time. The way your life goes is determined by what fills your time, what you choose to do. It's that simple. And scary, really. How easy it then becomes for your life to slip away without you actually doing what you want to do. There are so many options within any single moment, and it is only up to you to choose what is not only best for you, but additionally, what will further your desires for your life as a whole. Because you only reach the goal of passionate and fulfilled violinist by choosing to use your time in practicing.
The caution to "use your time wisely" then, is of relative meaning. Because time wisely used, absolutely varies by individual. Cleaning a house may be using time wisely for one, while making seemingly unremarkable phone calls is vital for another; because though a spotless house is certainly valuable, what sets it apart as a distinctly wise use of time is that it is immediately recognizable as such. The calls, however, necessitate a compilation before the result is seen: they allowed for greater networking, which made a connection with a certain person, who is able to offer a service or idea that eventually propels the person to reach their goal of self-sustainability.
In the end, the idea is simple and beautiful: do what you love and what you want to find value in, and there you will create and find a fulfilled life.