A Latin passive often has a reflexive or intransitive sense, saying what the subject does to itself or what simply happens to it: ferri "to be carried, to rush", distrahere "let yourself be distracted".
When a passive has no agent (a, ab) and "is …ed" sounds wrong, try an English reflexive or intransitive verb: feror "I am carried, I rush", moveor "I move", vertor "I turn", mutor, transmutor "I change", offendor "I take offence", delector "I enjoy".
In commands and wishes it means "let yourself be …" or "get …": nec distrahere amplius "and do not let yourself be distracted any longer"; huc illuc ferri desinas "stop being swept this way and that".
A phrase like sponte sua "of his own accord" shows clearly that the subject acts: sponte sua ad laedendum feratur "he rushes of his own accord to do harm".