Sadly, unless you happen to have a gun or a bottle of N there is no peaceful method, and even a gun can be quite frightening. The more peaceful a ctb method, the more it is targeted by the delusional and selfish pro-lifers who devote their lives to making sure we are trapped here in this hellhole. Ideally, we could walk into a euthanasia clinic and receive N, but that is so far away from reality that it's not even worth imagining. If you want to ctb, unfortunately it will almost certainly be risky and brutal.