Based on the sticky information threads at the top, it will be to the best of you advantage to be able to explain how well you excelled at an individual sport (example- If you placed or qualified for nationals, state, or won at region, etc)
90 percent of all successful applicants do a varsity sport; however, there are 10 percent that don't.
You are certainly not doomed.
From USNA1985's sticky thread:
"What sports does USNA like best?
There is no official policy on this. My recommendation is that, if possible, you should try to participate in at least one team sport. Being a good team member is good preparation for USNA. You may want to pick a sport that will force you to do a fair amount of running as this will be very helpful at USNA.
IF you pursue an individual sport -- one where you are essentially competing one on one vs. other competitors (e.g., swimming, diving, gymnastics, martial arts, wresting), it is important to demonstrate your level of competition. Thus, to the extent you are all-district, or a league MVP, or have the tenth best time in the state, etc., be sure USNA knows about this."