Keep putting yourself in successively more stressful situations on a regular basis until eventually everyday stress becomes an exercise in monotony and you can no longer understand why trivial things bother some people. Then de-stressing will no longer be required because you won't get stressed in the first place.

I run or walk. Clears my head.

I bundle all my stress up into a little dense ball that dwells deep inside my diaphragm. There it sits quietly, until like the inside of a golf ball, it unwinds violently, making breathing feel impossible. It's a pretty good system.

I masturbate

Sex and alcohol

Creative sex usually helps.

Ripping out weeds in my gardens is great during spring and autumn, winter= grabbing the axe, the steel wedges, the 10lb sledge hammer and the chainsaw (if needed) and splitting wood for the wood heater, it gets the blood flowing, the temperature up and I often imagine the face, etc, of some annoying person, problem, etc, being on the piece of wood.
As for the accursed Telemarketers/Survey Pollsters ringing my landline, well, answering and speaking in either German, Latin or some meaningless drivel language I've invented at the time usually annoys them and release my stress.

You had faith in God. It's time to put faith in people and government and assume that most will do the right thing, from teachers, to politicians, to everyday people. And that those who don't will be caught by practices and protocols set in place.

YouTube debates with flat earthers!!!

Breathe slow and loud; get into a good book; work up a sweat, usually a fast walk or an uphill hike; smoke a bowl; sip an alcoholic beverage; clean house; silly YouTube videos; sex (only this far down the list because I’m solo)
But mostly I avoid things that cause stress to spike, like TV news, any Trump news, cities, drama. Stress still rears is ugly head, hence the big bag of tricks listed.

Nothing relieves my stress better than a long hike

I do believe in the power of massage. The power of human touch and muscular massage can really de-stress and get those feel-good transmitters and receptor going with the good stuff. Even an inexpensive massage at the mall can do that for you. It does not have to be a $300 spa day. (And I'm not talking about the happy-ending kind at the asian massage parlor, either.)

What is this "de-stress" of which you speak?

Mindfulness meditation, exercise, sex (self & other), moderate alcohol consumption, hot tub, television.

Since you seem to be seeking things specifically to replace prayer, I would direct you to many, many options for meditation that are out there. I recommend books and audio programs by Zen Master Thich Naht Hahn and videos by deeply secular news anchor Dan Harris. There are even apps to guide you, such as Calm, Breathe, Insight Timer. I believe Sam Harris has even developed one called Waking Up.

Welcome to your new freedom!

Deep breaths are good, but deep drags on a pipe work better. Seriously, I de-stress by getting in my car and driving down rural roads (they are all rural roads here) while listening to Neil Gaiman books, or maybe Terry Pratchett's. Or late at night, I may have one or two shots of aquavit and listen to the Rolling Stones until the dogs protest.

For de-stressing I also like being near moving water, like standing in a mountain river. Something about the flow of energy and the ionized air. And i might as well catch a brown trout with a fly rod while i'm in there.

Count your Blessings. Nothing to to do with god... keep your eye in your Potential and how much you are Worth... to yourself. Peace.

@LisaL81 I like to go into a flow state.

Hope these little de-stressors of mine lead you to find what works best for you.

I walk a labyrinth if there is one nearby. Or, I take a hike in the woods, bring my hammock, and find a place to relax and enjoy the quiet.

A little scotch and a little weed, or when I am playing music. Sex works, but the other two are much easier to come by. No pun intended.

I meditate daily so as not to built up stress...intense physical workouts help me as well, especially if it involved punching something...

Petting my black cats seems to calm me down and take me away from it all...

I like all of the suggestions people have given...one of each works for me!

In general, even tough my life is not easy, I have little issue dealing with stress. Just the way I am wired, I'm certainly not special or in denial. To the extent I do feel any, exercise is best. A cigar with cognac is effective as well.

Yoga, meditation, weed, playing and/or listening to music, getting out in nature, exercise, hard work, and sex and/or masturbation seem to be the most sure fire ways to clear my mind. Hot tub, sauna, massage, stronger psychedelics and swimming are all primo reset buttons for me too but I don’t get to partake in them often.

Look back on my life and appreciate all I've experienced, the bad as well as the good. Look forward and know that there's more to come...

I love to read very much and a good book it usually de-stresses me.