His power

Church this morning.
This speaks for itself but it matches what the preacher (I) was talking about:

Do you not know?
Have you not heard?
The Lord is the everlasting God,
the Creator of the ends of the earth.
He will not grow tired or weary,
and his understanding no one can fathom.
He gives strength to the weary
and increases the power of the weak.

Those who hope in the Lord
will renew their strength.
They will soar on wings like eagles,
they will run and not grow weary,
they will walk and not be faint.

Isaiah 40:28-29,31

More on this here.