Most Helpful Guy
Everyone could stand to change at least a little. I know most people will say, "Just be yourself and the right person will come along." That is a load of bull and deep down we all know it. In any relationship, people need to make certain sacrifices to attract, and make the other person happy.
So yes you should change some things about yourself, but not to a point where you become unhappy as a result, or that you are pretending to be something you are not. Like someone else already said. You should be trying to change into a better version of yourself.
Most Helpful Girl
You shouldn't change yourself to get the approval of other people who don't even matter. Your ex is an ex for a reason. Screw what he said. If you were to change your appearance only do it for you and not anyone else. If someone can't accept you for the person you already are then screw them too.