Well dude if you got the talent and sense to visulaise, CG will help you alot to achive your vision really realistic,so Maya is just a tool wich needs to be learned.
It takes about 2-3 years to get comfortable with so your age is way too far of beeing too old to approach CG!

I'm 21--started 1 and 1/2 years ago!

So wellcom to CGI1