My job involves knocking on doors
why does your job require you to knock on doors?
I'm a salesman for my company so It's my job to go door to door.
You gotta do what you gotta do! I hope you like your job and the way that you get to meet a lot of people. Either way, it's good that you work hard and support yourself.
I don't really like it. I want to travel, but he's making me do this.
I don't know who you are referring to here, is it your boss who requires you to spend so much time going door to door?  If so, then you should fulfill your responsibilities on the job, but when you are able to, you should try to find another job that will be more enjoyable to you.