and yet, for some reason, it seems to be the hardest to implement
It's so hard to live by that Jesus had to lay His Life down to enable His Disciples to fulfill this commandment by which all Christians should live.
It is so much more difficult for those who are without Christ in this life, for a simple reason: They are without hope and headed for a place they wouldn't want their worst enemy to go. Additionally, it is not possible to love people as we would want to be loved without the Spirit of God, Who IS Love, abiding in our lives.
IF one thinks he/she is a Christian, let him/her check themselves and see how well they treat even their worst enemies: If you cannot lay your life down for the sake of your enemy's happiness in the SMALL things, I suggest that you are simply WITHOUT the Spirit of Christ, and would NEVER be able to live according to the Golden Rule of Christ if the things about your enemy were LARGER and HARDER to overcome.
Remember that Christ uses the story of the Good Samaritan to illustrate just WHO your neighbors are. They AREN'T always the people you've grown up around and come to love. Many times, they are your ENEMIES. So Christ is telling us to love ALL men, friend or enemy alike. And He requires us to treat our enemies as well as we treat ourselves or our friends. Additionally, HE desires that we CEASE passing judgment on others, so we have NO right to decide to treat one person (Friend,Family, or Foe) differently than we treat ourselves or other (friends, family members, or enemies.)
Christs' friends are those who are the friends of those in need, those hurting, those dying, those imprisoned, those oppressed, those murdered, those robbed, those without families, those without help.
Christ died to save the SINNER from his sins, not to throw them all into the Firey Pit of Hell. Don't forget that, and you will be more willing to love all men as well as you love your family, friends, and self.
Donald L McDaniel