We do not pray in our house, in part because I am an atheist. But atheism is neither a necessary nor a sufficient condition for abstaining from prayer, and I often find myself in public circumstances praying with groups of people. One such circumstance occurred over thanksgiving.
My wife's people (on her father's side) are Quaker, going way back. I sometimes chafe at some of their stiff, almost puritan ways, but they were protesting slavery and abstaining from war back when other religions--maybe yours--were still wondering if Indians had souls. Molly's Dad, Mike, maintains his faith is by having a silent prayer before meals.
After one such prayer over break, Caroline asked me "Why you pray?" It had taken a fair amount of shushing to get her to be quiet for a short interval, and she wanted to know what the deal was.
"I better let you field that one, Mike," I said.
Molly interrupted before I could finish, saying, "Tradition," a standard answer we give Caroline whenever she asks about odd human behavior.
"Mike, did you still want to answer," I said.
"We pray to ask the Lord for help," he said.
A little later, when we were alone, Molly asked me what I thought of the incident.
"I was surprised he went with petitionary prayer. That's never been my favorite kind."
"It is, though, something that an almost three year old could understand."
"Yeah, but do you really want to give a child a Santa Claus notion of spiritual life?"
"So how would you have answered?"
"I would have said 'I try to cultivate a reverential attitude.'"
You, the internet, may be asking "A reverential attitude toward what, Mr. Atheist Person?" to which I can only answer, “You know, stuff.”
Those who fetishize the ability of science to generate knowledge think that one’s emotional life is a random, insignificant thing. But emotions can be apt or inapt. In truth, apt feeling may be more important than true belief. So here is a minimal sense in which one should be spiritual. Calling you emotional life a spiritual life begins to grant it the kind of meaning it merits.
Update: Speaking of cultivating a reverential attitude, PZ Meyrs links to this incredible BBC video of slugs mating. PZ's right. If this doesn't make you feel a little homely and inadequate, you have no understanding of beauty.