Good Question! I think strenght is a quality that can be applied to physical, emotional, intelectual, or spirtual aspects.
In general, for me the idea of strenght means for me to be able to overcome a load through the application of maximum force.
So, I am being strong whenever I am exerting my maxium effort in the gym, life, etc.
In terms of a physical goal, I equate that to a 400 bench, 500 squat, and 600 deadlift. picking up and throwing cars would be nice, just dont think that is within my human realm!