idiom for "if you are not improving, you are deteriorating"

Is there an idiom or expression for "if you are not improving, that means you are deteriorating"

Thank you

Solution 1:

use it or lose it

Here's an example of usage:

Psychology Today

For several decades, people have used the term "use it or lose it" to aptly describe the best way to off-set the problems that come with aging.

In other words: use your brain, or lose your brain.

I usually hear this with the imagery of a rowboat: Like rowing a boat upstream, if you stop moving forward you fall back.

(searching for that phrase in google tells me that's a chinese idiom; I did not until just now know that!)

The more general phrase is: Standing still means falling behind.

(or similar variations like: If you're standing still, you're falling behind.