It's easy to get caught up in the college admission process and forget about the here and now. Going about the business of being a good student and good citizen, making choices for the betterment of your brain, body, and spirit, often offers more benefit for college admission than some plan crafted to impress college admission officers. So don't get involved in some activity just to impress colleges. You don't have time for that. Talk about it.
Senior year can be sad and exhilarating at the same time.
But you're also looking forward to graduating and starting college. That's how seniors feel. They have worked a long time to get to this point and should do all they can to enjoy it.