Is age really just a number?

As my 30th birthday approaches (December 31, 2010), I often find myself thinking a lot about age and what that number implies.  Doing so causes me to pose the question: Is age really just a number?

At the end of the day, I think that age is a mix of the following factors:

1) You are as old as you feel.
2) You are as old as you look.
3) You are as old as you act.
4) Your life experiences denote your age.
5) Age is arbitrary and means nothing.

Age can really confuse me sometimes.  I see 50-year-old women who dress and act like 22 year olds, and I see 16-year-old girls who look like they are 35.  Personally, sometimes I act like I am 13 (http://cestlaviebyelle.blogspot.com/2008/12/13-going-on-30.html), and other times 25 years of ballet make my body feel like I am 75.  I find myself having crushes on 22-year-olds and guys in their 40s all at the same time.  How is this possible?  What does all of this mean? 

I do know that too much makeup can really age you, baking in the sun and/or smoking will make you look 50 when you are 35, and getting enough sleep should make you feel just right.  I think it can get tricky when we are not where we thought we would be in life at a certain age.  For instance, I always thought I would be married with children at 29.  As He always does, God had other plans for my life, so I am trusting that He knows what is best for me at every age.  I guess all we can do is forge ahead with the confidence that we are exactly where we should be whether that is 13, 30, or 73.