THE FINE ART OF TOUGH LOVE. If you're lucky, somewhere in your past is that one person who changed your life forever. The one who pushed you to dream bigger and to reach higher, and who set you straight on what matters in life. Perhaps it was a coach, or a professor, or a family friend. For Joanne Lipman and Melanie Kupchynsky, that person was a public-school music teacher, Jerry Kupchynsky, known as Mr. K--a Ukrainian-born taskmaster...