What is old?

I remember as a child wondering what my life would be like when I was 50. I imagined that I would be alone and barely able to walk up the steps to where I lived. It took awhile for me to get there, but it wasn't at all what I thought it would be. I went to the gym six days a week and had an active social life. I was working full time and still taking classes to earn my doctorate. Not long after that I retired from my first long-term employment and was moving west to California to a new position. Then came 60. I had just completed my doctorate, married, and enjoying a Mediterranean cruise as a way of acknowledging my accomplishments. During this time I was making new friends from all corners of the globe. In my 60s I started my coaching practice, traveled to all seven continents, and began writing my first book. Along the way I would ask myself if I thought I was old. The answer was always the same. Old is a state of mind. As long as life is filled with new adventures and challenges I will never be old. I know that at some point there will be significant changes, but that is not today. Today is all any of us truly has. What does old look like to you?