Spirituality means something different to everyone. For some, it's about participating in organized religion: going to church, synagogue, a mosque, etc. For others, it's more personal: Some people get in touch with their spiritual side through private prayer, yoga, meditation, quiet reflection, or even long walks.
Research shows that even skeptics can't stifle the sense that there is something greater than the concrete world we see. As the brain processes sensory experiences, we naturally look for patterns, and then seek out meaning in those patterns. And the phenomenon known as "cognitive dissonance" shows that once we believe in something, we will try to explain away anything that conflicts with it.
Humans can't help but ask big questions—the instinct seems wired in our minds.