Not Getting Any Younger

The phrase "you aren't getting any younger" really hits home with me. I know to most I probably don't seem that old but working with kids all day will make you feel that way. With birthdays drawing near I see how my parents must have felt. My niece is soon to be three. Just yesterday it seems like dad and I were making that long trek through the snow and ice to see that beautiful bundle of joy. Now she's about to start pre-school. I feel old. I felt old when my fourth graders last year became fifth graders this year. This cycle will continue. That makes me feel old.
It is pretty bad but almost every night I lay there in bed and think boy I am not getting any younger. I think well I don't want to be old when I have kids, but I wanna finish my final degree. I think though I want to have more than one. So what does that mean. I just feel my own old age setting in and it is starting to scare me.