Among others, my friend just mentioned that actually even to walk should not be taken for granted. He just came out from operation a month back and of course he can relate closely to that.
I too had one experience sometime back where my back muscles were so pain I had to lay on bed for 15-20 mins. That made me appreciate what I have - and each walk, or like my friend said, each step.
There are other things in life that I sometimes take for granted too. But once in a while, I'll get this reminder. Let's just hope that it doesn't get too late to be appreciative and thankful :)