PSALM 73:26 INNER STRENGTH in your inner being.

Psalm 73:26  Good News Bible
My mind and my body may grow week,
     but God is my strength;
     he is all  ever need.

Psalm 73:26  English Standard Version
My flesh and my heart may fail,
       but God is the strength of my heart
       and my portion for ever.

In the New Testament, Paul is inspired
to give the same testimony as David.

2nd Corinthians 4
.......though our outer self is wasting away,
       our inner self is being renewed every day.
.......For the things that are seen are transient
       but the things that are unseen are eternal.

The Christian believer has an "inner self" and an  "inner life"
The inner self enjoys an ongoing relationship with the living God,
who is forever the source of his inner strength.
Note Pauls prayer for believers in Ephesians 3:16 KJV
      "That he would grant you according to the riches of his glory,
         to be strengthened with might by his Spirit in the inner man.
Ephesians 3:16 ESV
       "that according to the riches of his glory he might grant you
         to be strengthened with power through his Spirit
         in your inner being.......