And David was greatly distressed, for the people spoke of stoning him, because all the people were bitter in soul, each for his sons and daughters. But David strengthened himself in the LORD his God.
1 Samuel 30:6 ESV
The light of the eyes rejoices the heart, and good news refreshes the bones.
Proverbs 15:30 ESV
The line between thinking and physically performing is simpler to define in theory than detect in reality. It is easy to think one can separate physical weakness from discouragement, but the way the Bible speaks of strengthening ourselves leads to questions about such a separation.
I’ve written about how David strengthened himself in God and how Jesus did the same. Despite the risk of wedding the Bible to possibly soon-to-be-debunked science, I want to point out that we have good evidence to expect that encouragement makes one “stronger.”
There is really no need for quote marks. Encouragement makes it easier to perform. That is strength.
Or, to put it another way that comes more naturally to a glass-half-empty person like myself, discouragement weakens.
It is called the nocebo effect.
Consider this description of a study that experimented with volunteers by convincing them that thy did not get a decent night’s sleep:
Subjects then took several standardized, validated cognitive assessments involving rapid arithmetic, verbal fluency, and other tasks. The findings showed that subjects who were told they had slept poorly tended to perform worse on the cognitive testing, compared to subjects who were told they had slept better — regardless of how they actually thought they slept! In fact, the “assigned” sleep condition better predicted how subjects performed than the subjects own assessment of how they slept.
Thus, if people were told they did not sleep well, even if they had felt rested, they did worse on objective performance tests.
Getting discouraged, getting our expectations lowered, focusing on and anticipating negative outcomes, affects our ability to perform. Thus, raising expectations and reminding people of their hope in God is often referred to a strengthening.
For I long to see you, that I may impart to you some spiritual gift to strengthen you—that is, that we may be mutually encouraged by each other’s faith, both yours and mine.
Romans 1:11–12 ESV