Most of my pants are tight enough that the phone barely moves. For running I have a Flip Belt that securely holds it against my body without any risk of it falling out. https://flipbelt.com/

Don't see how front jeans pocket is too loose. Still not sure what your use case is, but you can try an arm band if you need constant access to it. If you don't like how it's slippery in your pocket, you can get a case with rubbery outside edge that will make it not slide. But that's could make it annoying to slide into you pocket.

Get one of those arm band cases so you can wear your phone like that thing Leela has on her wrist in Futurama.

Or spend way more for a smartwatch to essentially have the same thing but smaller.

Amusing. This conundrum, exactly as described, has also been bothering me, on and off, for years. Having tried a bunch of solutions, I have recently settled on one that I'm quite pleased with.

A bumbag. AKA waist pack. (AKA another name which sounds both comical and vulgar to British ears.)

You're not gonna look cool but it works.

One of my friends wears a lightweight (mostly mesh) cargo vest thing that looks good on him. But he's one of those assholes who looks good in anything. I would look like a doofus wearing it. Anyway, it has multiple pockets on the front.

Look up running belts.

The Unipörs is kind of an odd one but at least it's invisible under a jacket

I suppose you're wearing baggy clothes? Because I've never had this issue despite running and cycling a lot

Ive heard the prison wallet is pretty secure but accessibility might not be the greatest.

My outfits tend to have small pockets, my phone fits snugly with absolutely no room for anything else.

So maybe you just need smaller pockets or a watch phone thingy.

I have sprinted without this being an issue so color me very confused.

Do you wear very loose fitting clothes by any chance?

I wear compression shorts that have the built in phone pocket. Nice and tight against the thigh and it doesn't bounce around.

I usually get an Otterbox case for my phones which come with a belt clip.

I use a fanny pack when biking out running.

If you're wearing a jacket a chest holster could work, either one with a chest strap like
or if you wear your jacket open one without.

Waistband is the place to put it. Some running shorts come with a waistband pocket, in front is ok but in back is what I prefer. You can also get... A waistband with a pouch is the best way to describe it, just big enough for a phone and keys pretty much and you can put it under your clothes easily

Back pocket for me. Even at my most active I've never had it fall out. Just have to remember to take it out when you sit down.

I bike and I have a pouch that wraps around the strap of my messenger bag. The trick is I put it on the inside of the strap, between the strap and my chest. Accessible and immobile.

My opinion is you need to use a smaller phone. Then a regular looking running waist pouch, arm band, or even a good pocket will work. Look into the small(er) s24, iphone se, iphone normal, pixel, BLU or Tank brand phones.

( ͡° ͜ʖ ͡°)

Consider a watch with cell service?

I have much the same issue, when I can I like to wear jackets that have inside pockets to deal with it. Barring that, back pocket > front pocket > extra pockets IME

I have shorts, made by a company Pistol Lake that's unfortunately no longer in business, that has a phone pocket inside the pocket with a snap closure.

Now, one, it perfectly fits my G100 and, two, the rest of the pocket is gigantic. Like, full size Nintendo Switch in there with wiggle room but my phone doesn't move.

So, this may be silly but, see a tailor about adding a pocket if your clothes are baggy enough for it.

My running pants/spandex material have a stretchy pocket around the center of the back of the waist. I also hate bouncing while running and I never feel the phone when in the pocket. Still easy to grab, maybe a bit more practice to put back in the pocket but just as easy to take out as a regular side pocket.

Right back pocket in cargo pants or shorts.

Left hand is wallet, front left is small tool pouch, right front is edc tool, possibly keys, and context specific requirements.

Everything is instantly grabbable off muscle memory, and the pockets are perfectly large for everything without stabbing myself in the junk with keys.

When I run or ride, I stick my phone in my waistband. I have an Otterbox case which is pretty rubbery, so it grips well. If I'm running I do screen out and if I'm rising I do screen in just in case I eat it.