True story:
During one exercise session one of the officer candidates decided to DOR (Drop On Request).
D.I.: "Why do you want to quit, Candidate?"
Poopie: "Too old for this, Sir."
D.I.: "How old are you, Candidate?"
Poopie: "24 Sir."
D.I. looks around and says: "How many of the rest of you are over 24?"
At least 6 of us stood up.
The point is that as long as you are younger than the maximum age requirement you'll be fine.
Remember this...the program is tough and challenging, but it's designed to do two things:
1. Train the Officer Candidates who are qualified for the program to PASS the program.
2. To test your desire and dedication to complete the training.
If you want it badly enough, you won't have any trouble getting through. If you run into issues (for example, guys who couldn't swim well enough were held back until they could), the military will give you enough training until you can meet the minimum standard.
While this may seem simplistic, watch the movie "An Officer and a Gentleman" (minus the Hollywood drama) for a pretty good idea of what Navy AOCS was like back in my day.