Life becomes an examination when we don't know what we want from it, so we let it throw at us all kind of challenges for which we are not ready. Most of the folks don't know what they want, and they are constantly focusing on how to minimize or avoid what they DON'T want. Probably that's why some 80% of our daily thoughts are of a negative nature.
I am a pacifist, a meditator, a student of peace and harmony, so I can't be a good soldier, cop, or a butcher in a slaughter house. Being also of a pragmatic and logical nature, I can't be a good preacher. I got married when I was 20 for my teenage sweetheart. Too early? European baby-boomers matured much faster than later generations. I knew whom I wanted to marry, and 51 years later we still never raised voice on each other.
When you know what you want, life is a school that you chose because you have a passion for its "curriculum", not a school where you have to "struggle for good marks".
People get into wrong relationships, wrong friendships, wrong occupations, eat wrong food, and above all, allow the life to stress the hell out of them. Then every day becomes a test, an examination at which they are displaying their stage fright, not a mentality of a triumphant.
Then, it also becomes a matter of WHO are the examiners, to whom we give authority to tell us how good we are, whose approvals we need for our ego's survival. When we don't know what we want of life, then we allow others to tell us what to think, what is "appropriate to feel" in this or that situation, whom to love, and whom to hate. In that school we are bound to keep failing because we can't please everybody - let alone trying to please ourselves.
So, my bottom line is - life is not an exam when we feel that we are in our chosen field where we could teach - not learn.