There’s a difference between being uncomfortable and being in pain.
It’s healthy to test the limits of one, but not the other.
If a training session is simply hard, that’s good.
If a training session leaves you injured or unable to move afterwards, that’s not.
Hopefully under the guidance of a good coach, you can learn how to walk the line between the two.
If you do find yourself in pain during or after a session, that is a learning moment.
Did I perform this movement incorrectly? Was I not ready to handle that much load? Do I have an imbalance that need to be corrected? Was I properly rested and warmed up?
Should you attack your minds’ resistance to complacency? Absolutely.
Should you attack your own body beyond what it’s truly capable of? Definitely not.