I wanted to be an astronaut, animator, inventor, back to stop motion and time lapse animation and then physicist. I can't be an astronaut, but those other things are still achievable.
I don't see any immediate age disqualifications. Off to the races!
Eye sight and fitness may be blockers, at least if your not a certain senator from Ohio.
I'm pretty sure the oldest astronaut (real astronaut, not billionaire who bought a 10min trip) is currently still going to space and is 65. Conveniently I couldn't find a source so I could also be making this up, but I'm 95% sure.