Building off my original reply to this thread, that age factors in: It's common for people in midlife to assess their lives, acknowledge their lives are "half over", and wish they could go back and change things. The midlife crisis is hilariously unavoidable. It hits everyone in some way or another. If nothing else, it is a time to put our ducks in a row and make sure we complete more life goals.
So, that said, I would go back, but only if I had knowledge about the life I've lived, because if we have zero memory of having lived 20, 30, 40, 50+ years, what's the point? We'd have zero idea we'd been given the chance to live again, over and over. If we have no memory of it, we could argue that we already are being sent back to infancy to live our lives over in an endless loop, ad infinitum.
I like my life, I've had a decent life, and I don't necessarily have "regrets", but HELLZYES I would change things about my life if given the chance. And that, dear young people, is why you should listen to older people when we give advice. We have the experience and perspective, and we can see what you're up to. You cry that you will be different, but chances are you won't be. Get off the fucking Internet, get out of the bar or club, stop fucking off, and go make your goals happen now, now, now. Make sure you're living the life you want, not the life that is convenient, or the "pre-life" before your "real life". Your real life is now.
But of course... you think you have time.
I'd only make two changes, btw: one is about my university choices, and the other is about a personal goal from my childhood and teen years that I am just now fulfilling.