自 is "eye" plus a dot, which we'll call a splinter. JESUS said, before you make fun of the splinter in my eye, take check out the huge-ass log in YOUR OWNeye. Then he sort of muttered, "Ass!"
one's own (dog, blunt, fungus, etc.) - BOOBOO: sometimes it also is used to mean "you" or "she", as in "She did it herself, as opposed to having others do it for her."
自 (my own) + 分 (understand / divide / minute)
= 自分 (one's own)
Japan's army, in English called the SDF (self-defense forces)
自衛 (self-defense - usually used in 自衛隊 (Japan's army, the Self-Defence Forces)) + 隊 (troop)
= 自衛隊 (Japan's army)
自業自得
( じごうじとく )
"I brought this on myself!"
自 (my own) + 業 (business) + 得 (bargain / obtain)
= 自業自得 ("I brought this on myself!")