In my mid 20's, I hear that my life hasn't begun yet. But that sounds like a comforting head patting bullshit and I doubt it's going to begin in any prospect at all.
Life "begins" when you're ready. It sounds like head patting bullshit but when your physical and mental development completes at around 25 years old it only makes sense to count that as the beginning. Some people take their mulligan at 30 or even 40.
Life is too important for semantics like that. Do what you can, what you want and what you feel you should.
Life begins now. Every now. Use it or waste it.
But fr, people telling OP "your life is just beginning" mean that there is so much life and change that can and should happen in the next 20/ 25/ 40/ 60 years that you can't even imagine. If you've built a foundation, now is when you can START to build on it. If you haven't, you're not lost; there is so much time...but now is always the time to start.
One thing I've heard from a lot of people in their 20s (in school, not in school, whatever) is this idea that they have to know what they ultimately want or can't take a job that isn't ideal - and they end up in circles or paralyzed. But the real truth is that in most cases you can take on many, many different roles over time and hop/ get into completely new things - all throughout your life. The key is doing something and doing it well, whatever it is. Whether you like it or not, respect it or not, or want to be doing it for one more day or not.
But as for the "life starts at..," it is meant to buck you up. But it isn't false.
A friend of mine told he about her sons (early/mid-20s) recently. One, who has a fair amount of the tism and some other conditions, was working at some company on nightshift taking care of some kind of thing that is the key product of the company. Idk, involved a lot of sludge. Wore him out, kind of sucked, but he has stuck with it for 9 months or so, and he just sought, interviewed for, and got a job in the same company doing maintenance on their various industrial machines. Daytime shift, drives a cart, loves it, is thrilled. His brother has a moderate rap sheet, has been homeless, drugs, oppositional, lost his car, loves & has talent for chef work but back is bad so now is working at a kind of quick loan place doing clerk-type stuff, and is enrolling in college for a white-collar kind of degree. At their ages, though they're "behind" a lot of people their age, they have loads of time to get moving forward. And I'll bet that in 10-20 years at least one of them, if not both, will have a home, family, nice job (or whatever else is their idea of a good life). But neither would get there if they didn't start doing something. And that future life will have "started" now.
And to be clear, afaik neither of these guys had some amazing epiphany or developed a sudden passion and commitment - or certainty or amazing achievements. And afaik they're not secretly bill gates building a billion-dollar idea in the garage. They're just young guys who have had some struggles and difficult times from their teens on. And their younger/ youthful struggles will have shaped them and maybe delayed them a bit, but they've got everything in front of them / time to grow, go to school if they want, or take on/earn different and better positions, and start laying down some bricks of their future lives.
Can you do that at 50? Yes. Is it easier/ with more potential outcomes at 25 or 30? Also yes.
I get it's annoying to hear comments that may sound quasi-condescending. I suspect it's mainly people thinking fondly of youth and reflecting in how much has happened in their lives between your age and where they are now. Time flies (or maybe feels stagnant, which is a lie) when you're in it, but at a certain age, when you turn around for a second and look back, you really do realize just how much happened and how many opportunities there were for you over those past couple decades.
