Is age really just a number?

One of my friends posted a picture asking what people thought of the gray hair trend (just google "gray hair trend" if you're not familiar). I like the idea of any trend that embraces something we're culturally/societally trained not to be "ok" with. But what is it that we're not ok with? Is it just the mere reminders that we are getting older or that we're not the image we used to be? Would this model really think she was cool if they were actual gray hairs? I don't really mind the lines on my forehead but I mind the fact that they weren't there 3 or 4 years ago. Is it the change that we're not comfortable with or the projection of what might come next? I've been thinking about age a lot lately. I LOVE the Oprah Prime special with Cameron Diaz where she talks about aging as a privilege (a *must watch* if you ever catch it on OWN network). I'm really starting to believe (*actually* believe... not just believe in theory) that age is just a number. After a certain point in our lives where we are mostly done physically growing and we start the slow deterioration process, isn't it all relative? It may sound morbid (although I swear this actually makes me feel better), but after a certain point, we're basically just measuring an estimation of time until we die. That actually makes me feel good. In a lot of ways, I feel healthier with more vitality than I did in my early and mid 20s. I'm eating better, I drink very little alcohol anymore, I rarely get headaches, I haven't been sick once in the last 3 years, and I feel so strong and physically fit. If I had no reference point to my actual age, I can basically feel as young as I want to feel. What would happen to our perception of ourselves if we literally had no way to know our age? What if we were somehow able to delete the knowledge of our birth year? Would that better tune us in to how we FEEL more than wasting energy fearing hitting that next age milestone? This is all such a fascinating topic to me and I'm curious to hear your thoughts!