Movement, being a whole person, or having not lost a limb/body part that is necessary to modern living standards.

There are many people who are disabled in some way or cannot move correctly without help.

I work out on a daily basis, and I haven't missed a day in many years. I have nightmares about breaking my leg, or tearing some kind of ligament. It's a terrifying concept that I think about often. I have terrible eyesight(-8.00 for contact users), but losing or permanently damaging a limb or necessary body part is most likely my biggest fear. Keeping myself in shape has been one of the most important things for me to stay satisfied with my life in general, since you can always improve. Also the fact that I've been doing it for so long has made me somewhat attached to it.

Most people aren't aware of the intense pain that prosthetic limbs bring as well as the repercussions behind the surgery in general. You have to be able to perform in some intense physical therapy just to be able to move like everyone else moves. And you still can't really move as well. Also if you lose an eye, you're pretty much screwed. I almost lost one, it's not fun. You're immediately alienated from the rest of the world as soon as it happens.

It's not easy, but since then I have had not only extremely high respect for people with prosthetics just being able to live their lives normally, but I've also become a lot more careful with what I do with my body. Might not be spirituality/religion based, but it's an important point to make. A bunch of points have been made in the comments already but it's worth mentioning.