There are guys that can do very well without working beyond their capabilities on the biggest lifts, but those guys are few and far between. I guess it all comes down to; How much do you want it? The guys that really want it find a way to get after it, the guys who don't want it (deep down inside) will find any excuse to avoid it.
I have three herniated discs, displaced sciatic nerve, and a 65% disability rating...and squats and deadlifts are the two main reasons I can function normally now.
Some guys want it, some guys don't...just be honest with yourself.