I bought a ticket for myself. Change into passivevoice?

Active: somebody does something
Passive: something is done - (by whom may or may not be emphasized)

"Avoid using the passive voice." - active - subject: you (imperative) - verb: avoid
"Use of the passive voice is to be avoided." - passive - subject: use or using (gerund) - verb: some form of to be

Active: "I bought a ticket for myself."
Passive: "A ticket was bought for me."