Why does light speed slow your age down?

Good question. Never really understood this. So light speed is fast, so what? If I went at the speed of light to the (2nd) nearest star and back, the round trip should take me nearly 9 years. I would expect to see the world that has aged by exactly that amount of time! Why would it not?

Think of it this way:

You have Fred, who's about to embark on an epic journey to the next nearest star (4.3 light years away); and Fred's curvaceous wife, Wilma whose planning on timing Fred's journey because she's worried Fred might doddle (and by doddle, i mean bang Betty while he's visiting the star).  

So Fred hits the speed of light.  He looks at his watch and wonders if he's got enough time to bang Betty while he's visiting Alpha Centauri - To Fred, his watch moves normally (one second = one second).  To Wilma, Fred's watch would appear to hardly move at all; but to Fred, Wilma's watch would be moving proportionately as fast.

So to answer your question; to the one going at the speed of light, time passes normally, but slower to anyone watching.  To anyone watching Fred go to his booty call, time would also pass normally, but much faster to Fred.

I bel.eve time dilation is a myth. If there is a practical answer to this question it would be that at the speed of light no events take place, therefore you could not get older.

Look up the principle of equivalence. Do some research into general relativity.  Its interesting stuff.

According to the theory, because light is bent by gravity (which is experimentally proven) and all light travels at the same speed, light that is curved and covers less distance than another ray of light passes more time.  A good way to visualize this is to imagine three concentric circles.  Imagine the middle one is a large, dense mass. And the outer two are rays of light moving around the mass due to its strong gravity.  Now, both lights move at the same speed, and both will complete the orbit at the same moment.  But the one on the inside traveled through time slower because it had less distance to cover!