I'll tell you a secret if you promise not to let anyone know ...
It took me almost a year of weight loss and working out before I could do lunges properly. My sense of balance was (and still is) awful and my center of gravity kept changing with every ten pounds gone. I was about twenty pounds from goal before I consistently started doing them -- and they kicked my butt!
Sure, they're a fantastic exercise and you really want to keep working on them ... but no, the world isn't going to come to a screeching halt if you don't do lunges.
Does your gym have a hack squat machine, by chance? You can get a lot of the same benefits from one.