Ask HN: What is it like to be old? What advice would you give to younger people?

Physically, my best advice is to take good care of your back and your teeth.

These 2 things can make a huge quality of life difference once you are past 40. I would also add your eyes, but there is not a lot you can do about that one! Almost everyone needs reading glasses by 40. Glasses suck, but you get used to it.

Psychologically, the best I can say is to forgive yourself for any stupid things you did when you were young. Try to be as kind to yourself as you would be to others. I think of this as the "inverse golden rule." Really important as you get older, because regrets and self-doubt pile up otherwise.

Experience the benefits of fasting -- it will take care of excess weight and has other benefits.

This is not my advice - I'm 26 - but was given to me at school by a now-retired teacher I greatly respect. It sounds quite wise, and I trust the source.

I paraphrase: "Learn to classify people into three categories: givers, sharers, and takers. Surround yourself with givers. Sharers are also acceptable. Cut out the takers as quickly as you can."

A verbatim follow-on quote: "Takers make a beeline for givers. The needy are always anxious to drain the emotions and finances of those who are givers, before somehow or other they move on to sponge elsewhere, leaving givers to wonder at their own foolishness."

(Edit: apparently people don't want advice from older people to younger people if it's not the older person giving it. I can only apologise. It's the primary piece of concrete actionable life advice I remember that was given to me by anyone more than three times my age.)

Ride a bicycle and learn C (I've been doing the first for 50+ years and the second for 30+ [0]).

Some skills never go out of fashion.

[0] Personally, I found learning C harder than falling off bicycles.

> ‘What advice would I give my younger self’ also doesn’t compute. Because that would mean that I would end up with entirely different life experience and the person giving the advice would not exist as they would have changed. In sci fi, this would be the classic causal loop/temporal paradox time travel dilemma.

Are you actually worried that speculating about your younger self might accidentally erase you from the sands of time? We don't actually have a way of delivering our advice to our past selves, so the activity seems mostly harmless.