@mstub I'm not a doctor, so take this with a pinch of salt.
Keep going, but listen to your body. Make sure you know the difference between
"Oh, I can feel this muscle actually having to function" discomfort (good),
"Oh, I can feel this muscle group learning how to work in this new way" discomfort (good), and
"Oh, I can feel this muscle struggling / doing something which doesn't feel good" discomfort (baaaaad).
In the same way, make sure you can recognise the difference between
"Man I'm gonna feel this tomorrow" pain (good),
"Oh, this is new & yikes it's harder than it looks" pain (goodish), and
"Oh I don't think that was supposed to happen...." pain (baaad).
Everyone's bodies are different, but you
need to understand yours in order to exercise safely. What's safe for one person with an injury won't be safe with someone else with that same injury, and for someone else, it'll only be safe some of the time. Personally, I'm hypermobile - it means my joints have a habit of just dislocating when they feel like it. Sometimes, I can be active all day & not feel a thing other than a nice burn from actually using my muscles; other days, I can't even lift the kettle without my shoulder sliding out of place. That doesn't mean the kettle is too heavy for me, it just means the kettle is too heavy for me
at that point and I need to stabilise it more with both hands, rather than just the one. When I do shoulder exercises, I need to be extremly aware of how the muscles & tissue are moving around the joint, how everything is interacting, and how the muscle groups in my upper arm, back, neck & chest all interact and overlap and join together in order to know how my shoulder joint is going to react to them & how they're reacting to it. I used to be able to do planks, bridges & pushups without much issue - I loved mountain climbers. Now I haven't been able to do them in almost a year because I didn't listen to my body closely enough & pushed my shoulder too far; now I can barely put any weight through it without the muscles & tissue protesting. I'm slowly building the area back up, but it's a very slow process.
So if you do an exercise & it feels OK, then keep doing it. But just know that your body can & will sometimes tell you that even the most OK exercise
isn't OK
every single time you do it, no matter how many times you've done it before. Listen to your body. If you're hesitant about something, consider
why you're hesitant - is it because you think you won't be good at it, or is it because your body knows it isn't in a state to do it safely at this point in time? And if something hurts, don't just try to push through it - pay attention to what sort of pain it is.