As
@time2 says.
Your first job at USNA for all 4 years is stay sat in academic, military performance, conduct, PRT, honor and other areas.
First things first - get an appointment and get through plebe summer. Then figure out your priorities as the avalanche of ac year workload, plebe requirements, mandatory fun, watchstanding, etc., rolls over you. You’ll get plenty of briefs over the summer. Some are able to juggle a few ECAs and sail through their 4 years; some can’t fit any in, as they are struggling all 4 years. You have been a successful frog in your pond, but you will be in a larger pond of equally or more successful frogs. Time management, prioritization and self-discipline will be your top survival skills, at a level you likely haven’t practiced before.
ECAs are a great outlet and stress reliever, but you have to be strategic. You do them because you enjoy them, but you can also quit if need be - you don’t need them for a resume. D&B is a Brigade activity, I think, with long hours of practice. Sprint football is not an ECA but either a club or varsity sport, ditto practice.
One step at a time. Thousands of mids have figured this out before you. If you go there, you will too.