Commonly in strength training people will talk about this 1 to 10 scale of Relative Perceived Exertion (RPE). You might aim for an RPE of 7 or 8 on your lifts so that you're doing something useful for strength gains but sustainable.

Of course as an autistic trans person with some messy history of impaired interoception, it's not so easy to get an accurate reliable signal out of your body like that. Honesly about the best I can do most of the time is "challenging but won't injure me."