I don’t think I can be psychologically healthy without “disobeying” them. Haha.
Keeping mindless rebellion at bay, here, I strongly believe that every person should make their decisions based on what their needs and desires are, and not (solely) what their parents needs and desires are.
Our decisions should be governed by our needs, hopes and desires, as well as compassion towards parents (and others) needs/desires. It is easier said than done. I run into this problem every so often myself.
But over time my parents have come to realize that I make correct decisions for myself, even if they are completely contrary to their views. They have seen me take care of myself. After some dialog (often heated debate), they either see things my way or we agree to disagree.
When we agree to disagree, I often feel bad, depending on what the issue is. At that point, I talk to them (read: often fight) about what their reasons (usually fears) are about whatever I want to do. I figure out a way to either avoid any situations that scare them, or deal with them afterwards - and in some instances, disregard their fears (and throw a temper tantrum ;)).
So far, for things like majors and all, I have got them to see that I know what I am doing - with space for errors.
My parents views affect my life more than I want them to. But I still think I have amazingly understanding parents.