What would I pass on to my past self as an experienced developer?

Healthy lifestyle is your friend.

Without any excesses, of course. A healthy lifestyle is the same tool as work, only it converts time not into money, but into quality of life. There is no need to eat nettles and ski twenty hours a week in both winter and summer.

Get at least eight hours of sleep, eat healthy food, do light exercise – that's enough. Not only will the quality of life improve, but also its duration.

And all these hackathons, releases on Monday night and a refrigerator with energy drinks in the office are from the evil one.

TL;DR

Don't get caught up in this whole culture of productivity and proactivity. Life is an interesting and beautiful thing, you don’t need to bury yourself in the office, it’s just a necessary part of it. Not the most logical and far from the most interesting.

You write code to finally get a bike, give a girl a ring, buy your son a drone, drive to the mountains, build a bathhouse, go to a bar with friends, arrange a family cruise on a yacht… But certainly not to write code.