Progressive Overload
Your body only changes when you give it a reason to adapt.
Progressive overload simply means gradually increasing the challenge over time.
That could mean:
Adding weight
Doing one more rep
Improving your technique
Increasing your range of motion
Slowing the lowering phase
You don't need to progress every workout, but you should be working toward progress over time. The video below is a good example of progressive overload. You should be working so hard in each exercise that when you put the weight down, it feels like relief.