One of the great survival stories where the person overcame tremendous odds is the story of Hugh Glass. In 1822, Glass was attacked by a grizzly and left for dead by his fellow men in the expedition.

(From the Wikipedia article)

Despite his injuries, Glass regained consciousness. He did so only to find himself abandoned, without weapons or equipment, suffering from a broken leg, the cuts on his back exposing bare ribs, and all his wounds festering. Glass lay mutilated and alone, more than 200 mi (320 km) from the nearest settlement at Fort Kiowa on the Missouri.

In one of the more remarkable treks known to history, Glass set his own leg, wrapped himself in the bear hide his companions had placed over him as a shroud, and began crawling. To prevent gangrene, Glass laid his wounded back on a rotting log and let the maggots eat the dead flesh.
Deciding that following the Grand River would be too dangerous because of hostile Native Americans, Glass crawled overland south toward the Cheyenne River. It took him six weeks to reach it.

Glass survived mostly on wild berries and roots. On one occasion he was able to drive two wolves from a downed bison calf, and feast on the meat. Reaching the Cheyenne, he fashioned a crude raft and floated down the river, navigating using the prominent Thunder Butte landmark. Aided by friendly natives who sewed a bear hide to his back to cover the exposed wounds, Glass eventually reached the safety of Fort Kiowa.

I have the book "Hugh Glass" and it is a great read. If you ever see this book in a secondhand bookstore, it is well worth the purchase.