Going hiking in the morning

Nine kilometres, or about 5 miles. Normally this wouldn't faze me in the least but, umm, my back. My stupid crummy back that keeps betraying me. Scared. And on this particular hike, we are being dropped off at point A with our personal cars waiting for us back at point B. So if I realize that, due to my current back issues, I can't do the hike? I pretty much have to do it anyway. No pressure.