My wife is a runner. She has worked to increase her dedication to this endeavor in the last few years and continues to amaze me with her perseverance. She commented on her Facebook profile about a difficult run recently and her brother (who is a mega-distance runner) posted this underneath, "It gets easier, then it gets harder again, then you are better, faster, stronger."
What a powerful statement that isn't just about running. It's about parenting, marriage, devotion, Christianity, personal relationships, and career. It's the motto of following God and trusting in the way He makes all things new. It's a reminder that you sometimes have to be broken before you can be made wholly new again. The act of breaking is horrific sometimes, but the strength gained makes the new person that you become appreciate the process you endured. It's reason enough to keep putting one foot in front of the other.