School for Astrophysics?

I am 25 and am going to go to college, I am starting my frist year of my Undergraduate degree. I want to know from any Astrophysicists if the field is something that is prolonged that you will be able to do until your of an old age.

I absolutely love science and math. I have no problem with having to learn complex math. I will try forever if to have to. I have come to the conclusion that I need this. I do not want to have gotten old and referred never becoming an astrophysicist.

I know that there are certain scientific research fields where people who wait a few years to go to college are looked over for others that went immediately after high school. I want to know if Astrophysics has this sort of "thing" happening in the community.

I do not care if I work the rest of my life even just giving tours of a small observatory. I love science and astronomy. I love explaining things to people about the universe. I don't want to end up not having the chance to do this professionally.

So my general question is Is there any hope of me, being 25 and just entering undergrad school, having a career in Astrophysics? Please elaborate on your answer. Please do not answer with just a Yes or a No.

Thanks, Anthony.