What was your aha! moment for something stupid simple with gardening

The other day I was scrolling through Youtube and I thought I'd find some simple gardening videos to try and figure out why I always kill all of my plants when I feel like it should be something stupid simple. For years I've been resigned to saying that I just don't have a green thumb but after watching this simple video about pruning it was like a light bulb turned on. I had been trying to follow miscellaneous bits of advice like "use lots of mulch!" or "never prune your plants!" or "you need to have some sort of greenhouse effect to start seeds" without actually having a fundamental understanding of how plants work. I've done things like suffocating my seedlings, let things grow way out of hand so that they choke everything out, let my herbs bolt and die without a clue as to what I was doing wrong, etc. etc.

So for everyone else out there that does not have a green thumb or they have turned their thumb green through a lot of frustration and perseverance, I would like to know...

What was an "aha!" moment you had where you found a piece of information that was seemingly stupid simple but it made all the difference for you? This is likely something that the "experts" neglect to explain because it should be obvious (but obviously it wasn't for some of us).

For me, it was the fact that when you cut a plant it grows back. And you can control how it grows back. I guess I always knew this because things like grass grow back but for some reason it did not occur to me that an herb will grow back. i tried this on my sad sage and basil plants that I have growing in my kitchen window and the they are both putting out a million more little sprouts (branches? leaves?) and are no longer all leggy. Here's the simple video that I was watching:

Mine was realising I was watering on a schedule instead of checking the soil first. Killed so many things by watering every day out of habit when the soil was already wet. Once I started just sticking a finger in before reaching for the hose, things started actually surviving.

I love trees. I love to watch them grow big and tall and wild and free.

And then I discovered that big trees try to produce a lot of fruit. And that if I'm struggling to keep up with the watering they will then lose the ENTIRE crop and I get nothing. If they are kept small, they produce a manageable amount of fruit that I have some hope of using up, and it's easier to get enough water to the tree to support the development of that fruit. Also, when they are small I can fit more trees into the space available. And it's easier to pick the fruit because I can reach it.

We still have an enormous orange tree because I like to sit in its shade, and oranges drop when they are ripe so it doesn't matter if I can't reach them, and they ripen later in the year when there is more rain. But the fig tree has been hacked to about a quarter of the size it was last year and is doing brilliantly. And I'm busy imagining the maximum size I want the other fruit trees to grow so I can squeeze more varieties in between them.

Just because I love trees doesn't mean I have to have just a handful of huge ones - I can have dozens of little fruit trees that I can actually harvest and care for!

This is the book that finally opened my eyes - Grow a Little Fruit Tree

Chop and drop composting. Rather than spending time and energy carting my hedge and grass cuttings to the compost bin, storing it, turning it, then carting it to my plants, I just dump the mowing and clippings under the plants nearby, where they compost in place, while also being a great mulch.

I was frustrated that some of my seeds would get dug up, but I learnt, partly through experimentation and partly through someone here on the forums, that if I pull up grass and spread it out over where I just planted seeds the squirrels and stuff will mostly leave it alone, they won't see it as freshly planted/disturbed soil they'll see it as grass clippings and ignore it!
Its been a sloooooow process turning my dead thumb into a green thumb.  I was one of those people who would occasionally grow something and sometimes it would work and sometimes it wouldn't.  Then I decided I wanted to learn and its been 2 steps forward 1 step back, but its been worth it.

That if i let some plants go to seed i have enough to start over and share my passion with others. I learned to seed closer than recommended so the canopy closes and weeds have less chances. Just eat the small ones and let the biggest set seed.
Learning to closely monitor plants instead of overwatering.
I've battled a clover that spread like mad in the spring. Now i decided it represses grasses and explodes in time so i can easily cut it right in time to seed bush beans or sprawling tomatoes while fertilizing the soil.