Thirty was the year I had my first eye surgery. The eye doc said,"have surgery or go blind in that eye" something I had feared since I was a kid. Thankfully didn't go blind. Actually got off some of the eye drops, first time since about 11 or 12.
Forty I was feeling old and unsettled. Not married, not through school - very unhappy. Then two months later did go blind. Thankfully only legally - I grew up thinking blind was totally blind like dad. I could do either, but it is soooo much easier having some sight.
Fifty was a piece of cake. Actually happy with who I am. Helping dad out is great, even when its challenging.
You're not old until at least the 80's. My Granny Cook was killed in a car wreck at 97. So 30 is still wet behind the ears.