Contains

• endurance

  The power to withstand hardship or stress; "the marathon tests a runner's endurance".

• invulnerability

  The property of being invulnerable; the property of being incapable of being hurt...

• good part

  A place of especial strength.

• muscularity

  Possessing muscular strength.

• might

  Physical strength.

• vigor

  Active strength of body or mind.

• validity

  The property of being strong and healthy in constitution.

• ruggedness

  The property of being big and strong.

• stoutness

  The property of being strong and resolute.

• sturdiness

  The property of something that is strongly built.

• firmness

  The muscle tone of healthy tissue; "his muscular firmness".

• indomitability

  The property being difficult or impossible to defeat.