A true gentleman is polite to everyone, in action and words. Always be aware of how you can help people. Wait an extra few seconds to hold the door for the person behind you. Offer to help an old or pregnant person get their grocery bags to the car. You don’t have to be paranoid or risk killing yourself (i.e if you’ve got a precarious grip on something heavy, don’t open the door for someone) but respect is paramount. Even if someone is being stupid, be polite and respectful.