Argthtjtr

My friend and I were out in the rain, and I was asked why I left my stuffed animal keychain clipped to my backpack if it will get wet. I wanted to reply with an offhand joke about how being out in the rain builds character. Is there a German expression that means more or less the same thing?

Edit: No, this not a duplicate, though I acknowledge that there's a decent amount of overlap. However, the expression "to build character" in English can be used in a variety of contexts, some of them borderline flippant. I am US-American, and the context in which I see it most often is when parents make their children do something annoying or inconvenient for them (but is ultimately not a true "struggle"). My friend and I were joking around, referring to my stuffed animal as if "he" were a child rather than a keychain. I wanted to say something like "it builds (my stuffed animal's) character for him to be out in the rain." The expression here lacks the context to answer my question sufficiently and requires me to make inferences/assumptions I'm not necessarily in a position to make.

Thank you!

In the context of exposure to cold and rain I probably would have said:

Das härtet ab!

With this meaning of abhärten in mind: to toughen s.o, to build up s.o.'s resistance, to make s.b. stronger

You can say:

Im Regen zu sein stärkt den Charakter.
Being in the rain strengthens the character.

^{(also »festigt« instead of »stärkt«)}

But German native speakers won't say something like this in such a situation. If you walk through the rain, and someone asks you why you don't use an umbrella or a raincoat, or why you don't stay indoors, you say:

Ich bin doch nicht aus Zucker.
I'm not made from sugar.

With this sentence you say, that you're not touchy and you won't melt in the rain. (The word doch is a modal particle, this is a part of speech that doesn't exist in English. It just adds an emotion to the sentence. For details look at this question about »doch«)

So, when talking about your stuffed animal keychain you could say:

Das ist doch nicht aus Zucker.
It's not made from sugar.

In addition to @IQV's literal answer, there is a very similar but more established term.

den Charakter formen

or

charakterformend

It follows the gist of forming ones character out of wet clay. (Which is rather fitting in your rainy, muddy scenario)

"Nur die Harten kommen in den Garten"

In fact, the almost literal equivalent Charakterbildung (or Charaktererziehung — funny "erer", I know) does exist in German and perhaps is applicable in your case.

It's not so much about hardening oneself than about becoming self-reliant, trusting and trustworthy, a decent person, too. Becoming an adult. In other words, "building" a character which enables a person to successfully navigate their life.