Be mindful that it doesn't take a ton of weight to stimulate a muscle to grow, just the correct stimulus. Many people use too heavy a weight during an exercise, resulting in imprecise, sloppy form, exercising their egos more than shocking muscles into growth. It's the quality not the quantity. Short intense workouts are more beneficial. It's smart to vary your training routine to keep the muscles stimulated.
Recuperation is key to results.
Be sure to incorporate balanced rest periods into your training program. The aim should be to train or stimulate, not annihilate. To train in pain could mean over-training or a possible injury. Be as precise as possible and specific in your approach to training. I've watched people train without a structural format.