Not only are you challenging your lower body with paused squats today, you'll be pushing some heavy weight over your head as well, so get your head right before you get into the gym. The next few weeks will challenge your mind just as much as they challenge your body. Yes, you're going to be sore, and yes, you're going to be tired, but you're not going to die.
If you want a physique like Cory Gregory's, you need to follow the nutrition plan. Prepare your meals ahead of time, bring them to work or school, and you'll soon see that all those squats do great things for your physique.