To say your age, use “I am” or “I’m” – A NIE “I have”:
I’m 30 years old. = I’m 30.
NIGDY I have 30 years.
On your birthday, we use the verb turn to describe the change in your age:
I turned 40 last week.
My son is turning 16 tomorrow.
When talking about kids getting older, we say the kids are growing up. When a kid turns 18 (which is usually the age of adult responsibility), we call this coming of age.
Adults don’t grow up… adults simply get older. Another way to talk about an adult who has passed middle age (around 40) is to say the person is getting on in years. But if an older adult has a lively, energetic spirit, then we can say the person is young at heart.