"It was not meant to be." Those are the words of resignation, but they aren't for you. As the late football great Vince Lombardi once said, "Show me a god loser and I'll show you a loser!" No, you're not going down without a fight, and you're not all that keen to go down in the first place, so you're looking for strategies to get your ex back.
One strategy is to find out what they wanted in a relationship in the first place. What do they really need to be happy? Some people, let's face it, want a bed doll and little more. Some people are only in relationships because they're afraid of dying alone. Some people are only married because they can't conceive of themselves as a single person; they were raised with the expectation that their sole objective in life is to breed and that's all they're going to do. These may sound like belittling reasons, but of course even if there's more to the story, it still boils down to that. Nobody wants to face this about themselves.
One of the all-time strategies to get your ex back is to give yourself a make-over. This isn't just a matter of a visit to a hair salon and a manicure; this is an inside-out makeover. Start with your attitude towards life and work out from there. Maybe you were too demanding of others, or too lazy to put the work into a relationship in order to keep it. Maybe you could be more thoughtful of other people. Maybe it's the other problem; you put yourself last all the time, and your ego and self-esteem are so low that you're making a doormat out of yourself.
Out of all the strategies to get your ex back, one of the most essential is to make time for yourself and your ex to find your relationship's heart again. Put the world on hold and focus on just you again. For instance, when's the last time you enjoyed just lying in bed talking all night? No TV, no Internet, no phone, shut everything else up. And just focus on each other. It's amazing how everybody does this at the beginning of a relationship and marvels at how close they've gotten, and yet nobody thinks to do this when their relationship is in trouble.
"How do you get your ex back?" Be on your best demeanor and make your ex remember what attracted them to you in the first place. They'll remember your good points and will miss them. Then you'll have a better chance of getting back together with your ex.