It worked for Conan.
"Oh, I could never do that. I'd be afraid to put that much stress on my back."
I explained that you don't start training with 500lbs, but even so, stress isn't a bad thing. It's a stimulus, that gets a response from the body. The human body will adapt to a stress that is put on it. We want this to happen, because a lack of stress is also a stimulus. My friend wanted to protect his back, and so would refrain from doing anything that he perceived would cause stress to his back. How does his back musculature and skeleton respond? They get smaller and weaker!
Let me say this in another way: the strategy he has employed to protect his back is actually making his back weaker, and more likely to get injured. Counterproductive, right?
We all know that muscle atrophies when it isn't used, but bones do the same thing. Your bones are constantly undergoing a process of remodeling, where calcium is removed from the bones and returned to it. Calcium is important for the proper functioning of the rest of the body, and the bones are where it is stored. If you need more, the body will borrow it from the bones, and your body will repay the loan later. If you spend a few weeks on crutches, you could lose as much as a third of the mass of your femur, because your body thinks that it doesn't need to repay the loan. After all, if you aren't putting weight on a bone, why does it need to be strong? That calcium can be better used elsewhere.
Inactivity is not the answer. Find a competent coach, put your body under the right kind of stress, and get stronger.