Inner strength is not directly related to physical power or capability. Many who possess Inner Strength are not equipped for a specific task, which requires muscular strength. However, the possession of Inner Strength can produce achievement in an almost miraculous manner.

Neither intelligence nor other characteristics can be the yardstick by which Inner Strength is measured. The power of the will may be a substitute for inner strength by some people, but this power may fail at a crucial stage of effort. It also is true that will power can produce a plodding effort, devoid of imagination and effort.

The late Percy Wells Cerutty, comes closest to defining this inner strength characteristic, which is possessed by all great achievers:

"...to acquire these factors, whether as athletes or scholars, requires a capacity to take punishment, to survive the monotony of almost non- ceasing effort, and to learn to overcome the sense of futility, of frustration and to ignore discouragement."

Cerutty emphasized that the great achievers never entirely lose belief in themselves, never abandon their desire to eventually exceed normal expectations and achieve miracles.