What exactly does it mean, for you, to say that a person is responsible for a thing?

To me it means things like: you can reasonably be blamed if it's bad and praised if it's good; you have/had the ability to influence it a lot; someone wanting it changed would be well advised to go to you for help; it's the way you wanted things to be, or at least a predictable consequence of the way you wanted things to be.

If something happens to me by chance then by definition I didn't have the power to make it different, there's no point praising or blaming me for it; it has nothing to do with what I wanted.

(There are intermediate cases. Suppose I deliberately created a situation where a particular thing was more likely to happen, and it happened. Even if the processes leading to the thing happening were random, I could still be somewhat responsible for it. That's why there are laws around things like recklessness and negligence.)

If you reckon that everything that happens to you is your responsibility, it sounds as if you mean something very different by "responsible". But what?

another way that word is commonly used is to indicate the person who has a responsibility; the one who is tasked with handling a situation. ie "who is responsible for cleaning up this mess?"

I take it that's what was meant by the notion that you're responsible for everything that happens to you. In this case it has nothing to do with praise or blame. Rather, it means that whether something happened to you by chance or through your own fault, the onus to clean up the mess falls upon you.

Hmm, maybe. The way I'd say it is that dealing with whatever happens to you is generally your responsibility, not that the things that happen themselves are.

("Generally", not literally always. Extreme example: If you get hit by a car and your injuries put you in a coma, then both fixing the injuries and taking action against the driver if appropriate are necessarily other people's job.)

How are they responsible for what happens by chance? Do you worry your kids will grow up to idolize lottery winners? How do you think this attitude helps them?

It teaches them independence and agency.

As far as I can tell, my choices for dealing with injustices and terrible coincidences in life are:

1) to assume someone else is responsible to solve the problems for me, or

2) to assume I am responsible to solve my problems.

The former winds up leaving me bitter and angry with others in my life for not doing their job and taking care of my problems.

The latter helps me develop a sense of agency and helps me cope better with injustices and uncontrollable hardships in my life.

In this perspective, "fault" means "who caused this problem?", while "responsibility" means "who should try to solve the problem?"

Thus, taking responsibility for your problems doesn't mean assuming guilt for their existence.

This also applies in an inverse way to fortunate coincidences - in your lottery example, this mindset would say "I did not earn this money, so I'm not going to take pride in having won it, but I am responsible to use this money well."

This attitude also doesn't mean absolving wrongdoers of the harm they've done. Taking responsibility for healing the hurts others have done you may often include telling third parties about the harm and seeking help in repairing the injustice and preventing similar ones for potential future victims.

As that implies, "taking responsibility" for your problems also doesn't mean solving your problems solo. If help is offered, take it! If you need help, ask for it!

Just don't sit around waiting for someone else to deal with the hardships and problems for you, because that leads to despondency, disempowerment, and hopelessness.

That's how this has worked in my life, anyway. I really wish I'd been raised with this idea - I didn't encounter it until my mid-thirties, and it was a significant discovery for me.

I’ve grown very suspicious of utilitarian mindsets which essentially function by deluding yourself into something useful rather than truth being the motivating factor. Some people are actually disempowered and hopeless and delusions of agency are going to just inflict psychic harm upon them. I’ve seen severely disabled people take care of from cradle to grave for instance, trying to get them to take responsibility when bad things happened to them was just cruel typically.

I’ve been in situations in my own life where my situation was literally hopeless and I had to simply wait to get beaten badly enough that the authorities around me couldn’t ignore it. There was no third party to consult, no future victims to prevent (terrible burden to put on people by the way), no help to be had, I really had no real options. Sometimes all you can do is bide your time and taking responsibility is a stamina sapping waste of energy.

Agency isn’t simply a thought exercise and it’s not productive to simply just imagine that you have it. Taking the bitterness and anger you have at others not doing their jobs and directing those impulses inwards is hazardous and should be approached with caution.

I'm in no way trying to say that anyone can get themselves a good outcome by trying hard and believing they can. That's obviously fiction.

I understand, too, that I have freedoms and opportunities most humans never get, and that I can't truly understand the experience of someone who has been abused and beaten down, or of someone deeply disabled and unable to perform the basic mechanics of survival on their own.

I do understand that it's clearly a bad idea to tell people that they can do things the world has not left them with the capacity to do. You're certainly right that in many cases agency is partly or mostly lost, and then there isn't much can a person can actually do to help themselves. I'm sorry to hear that's something you've experienced.

I'm not suggesting that others should try to push the attitude I'm trying to describe onto others. I'm saying that I've found it very helpful and I'm trying to explain why.

I'm not recommending pointing bitterness and anger at yourself. Humans often do horrible, reprehensible things, and they should be held accountable for those things. We should never hold ourselves at fault for others' abuses, we should not pretend they haven't harmed us, and we shouldn't repress the emotions we feel in response to the mistreatment and abuse we experience.

I'm just saying that you can take responsibility for taking care of yourself, as much as you are able, while accepting any help and support you are able to find or that others offer.

The only alternatives I can see are counting on others to do it for you or giving up entirely.

I feel your comment is very much in line with my meaning; thanks

You're welcome. I'm glad I was able to help communicate your perspective!