Word on the street has it I'm old

According to a 6th grade patron I am old. Why? Well...

"Once you hit 20 you're old. I mean, you're halfway to 40."

He went on to inform me that one should retire at 25 because then you're really old. Here I was thinking that I was just about to enter the grown-up work force, just to find out that I'm retiring in two years. Damn. I don't think I can pay off undergrad and grad school in that time...