One thing that has become very clear through interviewing many people and studying happiness is that faith is necessary. Now this doesn't always mean faith in God or some sort of higher power, this could simply be faith in yourself, family or fate. The reason for this is that life is just too complicated and we can never understand it fully and that's just something we have to accept. That's not to say don't be curious about life but when times get hard you want to be able rely on something solid, something you know can get you through any situation.