That is one of my favorite video clips. I get chills and fight back tears EVERY time I watch it.
There is no substitute for perseverance. In the video the coach says, "It's all heart from here!" And it's true. Your heart - if it is right - will carry you through when times get tough, when everything in your body is telling your mind to STOP. Your heart is what will keep you going.
When I'm running and I get that side stitch, I've learned that the best thing to do is to run through the pain. I'm not gonna lie - I used to let side stitches get me. I used to think that I couldn't go on because of a little pain in my side. But there's always going to be pain along the journey, isn't there? And what good does it do us to stop moving forward to focus on the pain? Not one lick of good. In fact, I would strongly argue that when we stop to focus on the pain, we're doing ourselves more harm than good.
When the tide is out and you aren't sure if you're going to be able to make it - whether it's through a physical exercise or a stressful situation - dig deep and remember, IT'S ALL HEART FROM HERE!