In fact, it is not too late. The key lies in yourself and whether you are willing to work hard. I started learning it when I was 7 years old. It was boring and hard at first, and my hands also got calluses. But, slowly, you will feel the joy in it. You will feel the mood of the calligraphers and understand their stories from the books you copy; and learning calligraphy can also make you calm down and become more mature. Be attentive and more focused. So, 15 is not too late at all. If you want to study hard, go for it! !