Between being able to and ...

Between being able to and actually doing something lies an ocean, and on its bottom rests all too often the wreck of willpower.
 Marie von Ebner-Eschenbach

Quotes from the same author

There is only one proof of ability - action.
 Marie von Ebner-Eschenbach
Oh happy pessimists! What a joy it is to them to be able to prove again and again that there is no joy.
 Marie von Ebner-Eschenbach
To accept reason is impossible if you don't already possess it.
 Marie von Ebner-Eschenbach
Accident is veiled necessity.
 Marie von Ebner-Eschenbach
If there be a faith that can move mountains, it is faith in one's own power.
 Marie von Ebner-Eschenbach