Asking “How are you” in passing, is just another way to say “Hello.” People that ask are being polite. That’s all. If you don’t feel like pouring your heart out at the moment, just reply “Fine, thank you,” even if you feel like shit. But if you feel like talking, you’ve been given the opportunity. It’s up to you how you accept this gesture. Remember, when you change the way you look at a situation, the things you’re looking at change.