As the gardener, by severe ...

As the gardener, by severe pruning, forces the sap of the tree into one or two vigorous limbs, so should you stop off your miscellaneous activity and concentrate your force on one or a few points.
As the gardener, by severe pruning, forces the sap of the tree into one or two vigorous limbs, so should you stop off your miscellaneous activity and concentrate your force on one or a few points.

More phrases

Effort only fully releases its reward after a person refuses to quit.
Never complain and never explain.
A good plan violently executed now is better than a perfect plan executed next week.
 George S. Patton
Problems are not stop signs, they are guidelines.
 Robert Schuller
Never give up, for that is just the place and time that the tide will turn.
 Harriet Beecher Stowe

Quotes from the same author

Thought is the blossom; language the bud; action the fruit behind it.
The invariable mark of wisdom is to see the miraculous in the common.
Our distrust is very expensive.
Wisdom has its root in goodness, not goodness its root in wisdom.
Do not follow where the path may lead. Go, instead, where there is no path and leave a trail.