If you want to be a professional dancer, u have to start early and enjoy the little time u have for embracing this beautiful art. Some are lucky to be guided by parents from early stages, others (like me) have to earn money first to sustain dance classes.
Whether parents guide u through it or u discover it later in life, a definitely inspirational start point are movies based on dancers’ stories. For me, the most inspirational is Flash Dance, the one movie that started the 80’s pop trend of such subjects. Fame, Footloose and Dirty Dancing followed.
The famous individual practice of Jennifer Beals is both artistic and inspirational: http://www.youtube.com/watch?v=8NjbGr2nk2c&feature=related.