"I couldn't have recorded this record 15 years ago. My voice didn't have the depth to pull these songs off"

John Mellencamp's quote speaks with the power of experience and development. It suggests that he has actually grown as an artist and vocalist over the previous 15 years, which his voice has actually developed the depth and variety needed to pull off the tunes on his most current record. This recommends that he has been refining his craft and establishing his skills over the years, and that he has actually become a more fully grown and capable artist. It also indicates that he has actually gained a higher understanding of the music he is producing, and that he has actually ended up being more positive in his capabilities. The quote is a testament to the power of effort and dedication, and it acts as a tip that with time and effort, we can all become better at what we do.