Last year, I started meditating daily (usually only 10-20 minutes, sometimes twice).
3-4 months into the practice, I am still a n00b but have honestly told a couple friends already that this was one of the most life-transformative things I have intentionally done, except maybe for moving to Japan at age 19 (where I ended up mostly sticking, for decades now).
I really think YMMV on this one. I personally had one of those personality types (or more accurately, set of personality traits) where meditation probably has relatively major impact. Like, I was never not thinking about stuff. Usually, interesting problems in software engineering, for work or for hobby. But also home upgrades, DIY contraptions, am I doing well as a parent, should I get my kids a pet, how can I learn cooking/photography/piano/video-editing/martial arts/horticulture/etc on top of the stuff I am currently doing, etc.
And if I wasn't thinking about something, it felt terrible, like a true waste of time, the most precious resource any of us has!
Probably not coincidentally, I fucking HATED meditation whenever I had tried it previously (usually at the behest of some friend who advocated for it).
And I initially thought I was "failing" and "couldn't do it". I mean to say, I felt like I couldn't achieve meditation. I was just sitting there, doing nothing, having my usual nonstop thoughts about quasi-random shit. I couldn't "focus on my breath" (the usual beginner object of attention, before moving on to other sensations, thought and feelings, or aspects of the current environment) for more than like 2 seconds, literally.
After 3 weeks or so, though, I learned more and realized yeah that is part of it, just keep practicing and you'll get it. And you do still keep getting lost in thought, that's OK and normal, its the practice of noticing those thoughts arising, and returning attention to _____ that is a major part of the point.
After a few weeks it is obvious that paying attention (aka "being mindful") is a trainable skill, and practice yields improvement.
The TL;DR thing about it, the `n00b gainz` part that I think anybody can get, unless they already naturally have it, is: most of the thoughts you have that feel like "you" aren't, really. They are largely just thoughts. You feel like you are having them, thinking them, but generally that's not the case. Pay close attention and you can see the gap clearly between almost all thoughts that arise and "you".
It is then much easier to respond to thoughts and feelings in the way you actually want to, rather than in some reflexive way that is not actually they way you would like to respond.
The good thing about meditation is that you can just run your own n=1 experiment and try it. I chose the Waking Up app as my coaching tool (a real human teacher might be better, if you found the right one, but any of the apps will probably work fine I think) because it started with that premise: don't take our word for it, try this yourself and check the result for yourself.
I did so, and the results have been pretty subjectively fantastic. I'm more present with my children. I am less reactive to (and therefore significantly less irritated by) dumbasses at work and in general life. And it feels way, way easier to stick to every mundane goal (running every morning before kids wake up, going to bed on time, adhering to my physical trainer's diet, and any and all other shit like that).
After doing sitting meditation practice for a few months, I added walking meditation, which is fucking fantastic.
This experience has made me want to try fasting, which I have never tried but other people recommend a lot, including in this very thread. Like meditation, it isn't something you have to take anybody's word for. You can just try it yourself, and see what the results are.