BTW there's no evidence that the word has Turkic roots. "Keyif" means "enjoyment" but Kefir has no shared roots with it and "keyif" itself comes from Arabic.

Whatever its original root is, last verifiable root is Russian "кефир", according to Sevan Nişanyan ( Turkish: https://www.nisanyansozluk.com/?k=kefir )

I tried keeping kefir grains for several months and it never really turned out in a way that I thought was worth the bother.

I absolutely love the kefir you can buy bottled in stores, but maybe that isn't really anything like traditional kefir?

I get the same sensation when eating other fermented foods, like sauerkraut (which is also very easy to make, just pulverized cabbage and salt). I assume it's my gut flora sending happy signals to my brain.

What is your method? I’m a champ at making yogurt, but my first foray into kefir went horribly wrong.

1. Put kefir grains in milk.

2. Wait maybe 24 hours at room temperature, depending on preference. I regularly do 48 with no problems.

3. Remove grains and eat.

Can you reuse the grains? If so, how many times until they stop working?

I've been using a set of grains since 2017 or so.

Since they're essentially a symbiotic culture of bacteria and yeast (SCOBY), they won't "stop working" as long as the grains are regularly replenished with milk, or kept in the fridge to slow down the fermentation process.