Supernatural made me realize how important my family and friends were, and to always fight for them if something were to happen. I have my own siblings, and we fight all the time, with name calling, insulting, and worse. I watch this show and I see a family relationship besides the demons, Angels and whatnot.
Another thing is how I saw the world. Watching through Dean and Sam's eyes as a hunter brings a whole new perspective on the world. Other than the monster killing or the storyline, Supernatural shows ways to handle things, like what to do with a person that is broken and needs help(like when Sam helps Dean or when Dean helps Sam or Cas), or how to build up confidence in someone who may not have any(when Sam helps out Charlie using Harry Potter).
This show has really shown me things that I think about almost every day, other than how much I wish I could have Dean to myself haha. I'm really thankful for this show and I'm glad that I have been able to enjoy every last bit of it.