Are we satisfied with our jobs?

Someone mentioned in class today about their dad being unhappy with his job as asst.principal in elementary school. I would say that if he really wanted to become a lawyer, he could have been a lawyer. Same with my dad too. He was a college professor in India. He taught economics and finance. But when he moved to US, he couldn't find a job that he liked or he is not satisfied with his job. He tried many jobs before and now he is working at a store where he gets good amount of money without no complaints. I feel like same things would happen to teenagers too. I don't really see a point of taking MCAT's to get into medical school. Person wit 4.0 GPA can get rejected from med school if he/she doesn't do good on it. Even my brother is worried that he might not get into Med school because he did bad on MCAT. He has a GPA of 3.75 here and he's going to take it over again next semester. I am a bio major but i wanted to become an engineer. My parents asked me to go to same college as my brother it would be easier for them to come visit us. But now i feel like they were right about me being a bio major after the economy went down.