How do you stop aging?

So, time is relative.

So depending on our position and speed, time can appear to move faster or slower to us relative to others in a different part of space-time. And for astronauts on the International Space Station, that means they get to age just a tiny bit slower than people on Earth.

The phenomenon is called "gravitational time dilation." In a nutshell it just means time moves slower as gravity increases.
That's why time passes slower for objects closer to the center of the Earth where the gravity is stronger.

There is also something called "relative velocity time dilation" where time moves slower as you move faster.

Time gets even more complicated because gravitational time dilation and relative velocity time dilation can happen at the same time. A good way to think about it is to consider the astronauts living on the International Space Station.

They're floating about 260 miles above, where Earth's gravitational pull is weaker than it is at the surface. That means time should speed up for them relative to people on the ground. But the space station is also whizzing around Earth at about nearly five miles per second.

That means time should also slow down for the astronauts relative to people on the surface.

You'd think that might even out, but actually their velocity time dilation has a bigger effect than their gravitational time dilation, so astronauts end up aging slower than people on Earth.

So the next time you find yourself wishing the weekend would last longer, stay low to the ground and move really fast. It won't feel like your weekend got any longer, but technically you may gain a teeny, tiny fraction of a fraction of a second.

https://www.businessinsider.com/do-astronauts-age-slower-than-people-on-earth-2015-8