Hi,

As Pilou said, 2D/3D isn't reserved for young or more old peoples.

If you want to do something, Do it !

Modeling is more a research on "How to do" and practice more and more. Analyse and resolve problems to reproduce shapes.
For me, it's like programing software. Analyse the needs, resolve the problem to find how to do something.

I understand, you could have a doubt about how to be engaged as professionnal in an entreprise as you begin at 28.
But your age gives you experience in more domains.
If you really want to do it, believe in you.

But you have to practice more and more.
Talent exists, but without working and practice, it's not enough.

... And please, don't model always weapons and robots as many people do...
We have so many other subjects to model...