Choosing your friends is so important. Whether you intend for it to or not, it truly defines who you are.
1 Corinthians 15:33 says, "do not be misled: Bad company corrupts good character."
Even with the purest intentions, you still end up conforming to your surroundings. When choosing your friends, it shouldn't be about who's the nicest to you, what that person can do to benefit you, or even what you have in common that draws you together-- it should be your common interest in wanting to look more like Christ.
Our friends define who we become.
Proverbs 27:17 says, "As iron sharpens iron, so one persons sharpens another."
Surround yourself with friends who go deeper than the surface-- who care more about your soul than your outward appearance. Those are the friends who are going to stick beside you when all else fails.
As you get older, you realize that it doesn't matter how many friends you have, it's about who you can call when it seems the whole world has turned its back on you.
Proverbs 27:9, "a sweet friendship refreshes the soul."