As for not always having your phone with you, you can print out one-time passwords. So you print some out, put them in your wallet (and maybe more in your home)

As for not always having your phone with you, you can print out one-time passwords. So you print some out, put them in your wallet (and maybe more in your home), and then if you don't have your phone/your phone breaks/whatever, you can use one from that list. But then that one off of that list is dead. Also, I'm pretty sure there's some option where it only does the 2nd factor once a month if it's on a computer it recognizes.