A sneeze jolts your head. A friendly slap on the back makes you lurch forward.
These experiences create g-forces, or gravity forces, five times greater than the gravity you’re used to. Each experience lasts only a second, so you don’t pay much attention to it. But if any of them were to last longer, you would surely notice their effects.
The same is true for a microgravity, or near-weightless, environment, such as on the International Space Station (ISS). A few seconds of microgravity wouldn’t have an effect on your body, but if you were spending any time on the ISS, the effects would be noticeable.