do (oneself or someone) an injury
To do something that harms or injures oneself or someone else. You'll do yourself an injury if you keeping riding so carelessly. You sure did your brother an injury by including him in that dangerous game.
do yourself an injury
suffer physical harm or damage. informaldo somebody/yourself an ˈinjury
(often humorous) hurt somebody/yourself physically: I nearly did myself an injury carrying those heavy suitcases.