Better do a little well, than a great deal badly.
A jack-of-all-trades is king of none.
I started concentrating so hard on my vision that I lost sight.
The successful warrior is the average man, with laser-like focus.
You can do anything, but not everything.
Take up one idea. Make that one idea your life think of it, dream of it, live on that idea. Let the brain, muscles, nerves, every part of your body, be full of that idea, and just leave every other idea alone. This is the way to success.
You cannot depend on your eyes when your imagination is out of focus.
For purposes of action nothing is more useful than narrowness of thought combined with energy of will.
The ability to focus attention on important things is a defining characteristic of intelligence.
It is a far, far better thing to have a firm anchor in nonsense than to put out on the troubled sea of thought.