No matter how many times the entire universe goes out of its way to make him fail, Peanuts' Charlie Brown will just get up and try again out of sheer optimism. He'll whine, but he'll never surrender. Charles Schulz is quoted as saying, "Someone once referred to Charlie Brown as a loser. That never occurred to me. A real loser would have stopped trying."
No matter how many times his business plans backfire, Sam in Sams Strip never gives up. He just switches to a new plan.