We can't love truly those we don't serve - those we don't get to know personally - those we shun and avoid. There's no way around the need to risk pain and rejection if we are to "love one another as I have loved you" - especially since he also said that we are to love those who don't love us, since even the publicans love those who love them. We have to start where we can start, but we also have to reach outside our comfort zones at some point.
I believe it helps to identify those people in your own sphere of influence who constitute the "lepers, publicans, sinners and Samaritans" in your own eyes - and then consciously choose a way to serve somebody in that group of people. Once you are comfortable with that effort, pick another person or people to serve - until, gradually, you are able to serve anyone whom you feel impressed / prompted to serve. Just make sure you are doing so with NO other motives - not to convert them or to have them thank you and bless your name or for recognition or any other "compensation" of some kind.
Start perhaps with someone who has no reasonable way to pay you back in any way - or even to acknowledge your effort positively - or even to value you as a person or Mormon. It can be a painful process at first, but it is a powerful one.