Others have already pointed out better ways of doing this. But to answer your question as to why your current code is not working, it is because you need to use the index i in your code. E.g.,
ageless = [ageless age_vec(i)];
agemore = [agemore age_vec(i)];
This will incrementally build up the ageless and agemore vectors, but at each iteration you will have to deep copy one of the vectors, so the performance will be severly impacted as the size of age_vec gets large. Hence the desire to use a different method as others have suggested.