Remember that by accepting and doing with single-mindedness, you're not giving up on your goal. What you're doing is giving up the insistence that your goal manifest only the way you want it. You are accepting reality, embracing truth. You continue working toward the goal, but you've let go of your attachment to the results. In this way, it's like a game - you know the rules, and whether you win or lose, you can just focus on having fun playing the game.
Mental exercises can be powerful tools in developing the spiritual strength of surrender.
Settle on the relationship that is your heart's desire. Visualize what that whole thing would be like - the scenes, smells, even the emotions. Feel what it would be like, simply being with that person. Now, give that up mentally. See yourself handing the thing that's bothering you to your higher self - just give it away.