world on one's back n. phr. A very heavy load of worry or responsibility; very tired or worried behavior, as if carrying the world; behavior as if you are very important.
Don't look as if you had the weight of the world on your shoulders, Henry, just because you have to mow the lawn./
John acts as if he were carrying the world on his back because he has a paper route. [TahlilGaran] English Idioms Dictionary ▲