"Strength doesn't come from what you can do. It comes from overcoming the things you once thought you couldn't."- Rikki Rogers.
Strength is not through what you can do. What you can do is a given and doesn't in a anyway challenge you.
"Strength comes from doing that which seems impossible, something you never thought possible, something whose thought puts a scare in you and making sure to not stop until a win is achieved."
Man is programmed to be careful and to fear failing even without trying. Many will tell you they will rather fail that try at something they "know" they cannot get a win over.
The beauty of life is not necessarily in the materialistic aspects or the things we find come easy to us, it is in the never-give-up attitude we display with a resolve that sees us being crazy enough to defy fear when everyone else is sane doing the wrong things.
What happens to you is not strength, anyone can have terrible things happen to them. What counts is how you tackle that which happened to you.
Strength doesn't come from what you can do, (you can get really comfortable knowing we can do stuffs). Strength comes from overcoming the things you once thought you couldn't (by stepping out to take the bull by the horns).