It gets better and better if you don't quit your creative practice. Lets look at Nels Cline, the guitarist for Wilco. Now he is very successful,but for most of his life, up until he was over 50 he was a starving jazz guitarist. He never gave up his practice. For some musicians they suffer injuries or health issues that end their career. But as long as you stay healthy and limber and keep up your practice you don't start having issues until you're starting to get close to 80.