What I often reply to my clients is: “Are you injured or are you hurt?”
There is a big difference between being hurt and being injured like having a real muscle issue or joint problem. If it’s the case, you need to take care of it immediately. If the movement is uncomfortable but possible with a few warm up sets, then you are just sore.
This is one situation where mobility work comes in handy. Packing all these muscles but not being able to move them is pretty useless. The myth of big muscles and being stiff is in part right. The problem comes when you train but can’t use the complete range of the movement. It will often lead to structural issues. This is when things go bad. Shoulders, knees, ankles, you name it. Any structural issues will shift the load where it shouldn’t be and there goes the cascade of issues.
A nice little warmup will tell you if you can train or not. Let’s say you are about to do squats, start by stretching the low back, hip flexors, ankles and do a few reps of bodyweight squats. Then grab a barbell and do a few more reps, slow and steady. If the pain doesn’t go away or worse, if it increases, I would advise you not to train. Soreness will just go away after a few warmup sets.