Yes, You Can

I met someone, recently, who had a brain injury.  She said she "couldn't" control her left arm.  I suspect she had some control over her left arm.  She said she couldn't based on society's interpretation of the words can, and can't.  We too often say we can't do something when we have a difficult time doing that thing.  I use to say I couldn't control my left appendages.  I just have more difficulty controlling them than my right appendages.