It’s easy to push yourself to the end and finish your reps no matter what. I had done that for many years when I was younger. During my workout, I would start to get tired and notice I was no longer doing each rep with proper form. But, either due to my own personal desire not to let the workout “beat” me, or to give up in front of the other people training with me, I would keep on going.
I would usually be painfully sore for the next few days – and not the good kind of sore, but the bad kind that means you don’t do other workouts because your shoulders are in too much pain, or your lower-back hurts too much to bend over. Completing your workout in those types of situations is good for your mental fortitude, but it sucks for your body.