i know what you mean about these phrases feeling condescending sometimes.
the way I've used "don't borrow grief from the future" in my own mind is to help me when I am having disruptive intrusive thoughts about worst case scenarios.
for example, I do often worry about loved ones dying suddenly, and sometimes that worry can intrude on whatever I'm doing in the moment and take me mentally all the way into a future where that happens and make me feel severe grief despite the fact that what I'm imagining isn't real yet.
and it's certainly possible this worst case scenario could happen, and there is a practical amount of thinking and planning and speculating that can be done, and a reasonable amount of melancholy bittersweetness that i do appreciate a lot from knowing that this can and do go wrong without warning, but for me the intrusive thought takes me far beyond any useful response, and can put me in the acute emotional distress that I would be in in that situation despite that situation not being real at the moment.
and what I've learned from experience is: practicing that acute emotional state does not actually prepare me much for it in future.
I'm not going to control or prevent any aspect of my future emotional grief and distress by also feeling that grief and distress now just in case. I'm mostly making my present moment more difficult. but sometimes i feel like i owe it to future me to feel bad now too, even tho i bet future me doesn't actually want that.
so I guess for me it's explicitly not advice against doing any kind of practical planning or preparation, it's advice i use for giving myself permission to stop engaging with the catastrophic possibility before i go down the emotional rabbit hole that can be very paralyzing.
i mean, I think people often use this phrase in regards to worrying about much less emotionally fraught things, but this is what the phrase helps with for me, privately.
dunno if that helps or just muddies the water further tho!
