You must define what is "making a long distance relationship work." Do you mean it leads to a marriage or is it just a certain amount of time as in a year, two years, or three years...etc? One major error people make with LDRs is confusing (calendar time) with (actual time together). A couple that has been together one weekend per quarter will say they've been "together" for a year but in truth their "actual time" together would be (8) days.
Long distance relationships were meant to be temporary. The goal is to be with the person you love. When there is no "count down" towards the day when one person moves it's likely one of you will eventually want to throw in the towel. At some point someone has to make a move. A long distance relationship without “a light at the end of the tunnel” is likely to fail. It’s the counting down the months, weeks, and days until you are finally done with the inconvenience of being in a long distance relationship that keeps it strong.
The only reason for being in a long distance relationship is the belief she or he might be “the one”. If you’re just passing the time with someone you might as well do that locally.