I don't have any experience with Clozapine unfortunately, but I am on a medium-high dose of Escitalopram.
Personally, it took away that always sluggish, forever tired feeling that hung over my body like a cloud. Once the meds really took affect, I realized I physically felt better, and had more energy to actually do things. Keep in mind these are things such as, going for a walk or standing up for a few hours at work. Nothing like suddenly exercising or anything truly mind blowing. They're definitely nice to have and I don't think I'd go off them until I've been cleared to do so, if I ever get cleared.
The withdrawal symptoms if you forget to take them though are a PAIN IN THE ASS. The nausea, the headaches, the vertigo, the body aches... imagine trying to deal with that while walking a mile to work and talking to people face to face all day. Miserable. Don't forget to take your meds, man.