e body in
determination would be a strain likely to weaken your power of action
unless backed by a tremendous, stored-up reserve strength of muscles.)
Begin your practice for the development of determination, then, by
training your muscles to tauten the instant you think determinedly. Your
brain-mind center of determination will also be strengthened by the
exercise that builds up the supporting habit of muscle action in
coordination. Millions of men have failed in life because their
determined thoughts were not reenforced by stiffened backbones.

[Sidenote: Discrimination Between Determination and Persistence]

Now let us discriminate between muscle training to develop the
characteristic of _persistence_ and the training already described for
the building of determination. In order to strengthen your persistence,
you must transmit through the distinct brain center of persistence to
the corresponding mind center, the impression of muscles _permanently
developed in firmness_, not just capable of temporary hardening on
occasion.

The _characteristically persistent_ man has gradually developed his
lax-muscled, sagging, baby chin into a jaw that is habitually firm,
whether or not he happens to be determined to do anything at a given
moment. His muscles do not sag utterly, even when he is asleep. He
probably wakes up in the morning with his teeth clenched. So, whenever
his coordinated brain-mind center perceives that the quality of
persistence is required, and starts to apply it, the _mental impulse_ to
persist is backed by a _permanent firm muscle structure_ that can stand
up as long as the mind needs the physical support.

[Sidenote: A Slump in Determination]

In contrast, the man who is only characteristically _determined_, but
who lacks _persistence_ in his determination, has developed just the
habit of hardening his muscles _for the time_ he is determined on doing
a particular thing. That does not exercise his muscles sufficiently to
make them firm _all_ the time, whether under tension or not.
Consequently his determination is likely to slump if his resolution is
subjected to a long strain. He does not possess muscular structure
sufficiently strong to support persistence in his determination.

_Habitual lack_ of firmness in the jaw muscles, as you know, results in
a sagging chin; which detrimentally affects the brain-mind center of
persistence. A man whose jaw habitually hangs loose may be capable of
great _determ