The Old Testament declares believer's gladness.
We are glad when God is our habitation. Our joy is internal and private, becoming outwardly evident to our nearest loved ones, overflowing to our spiritual family, radiating to a Christ-less society and to an antagonistic world. Gladness comes from personal righteousness and is manifested continually. Rejoice every day. Approach God with joy.
Verses to consider.
Psalms 9:2
(2) I will be glad and rejoice in thee: I will sing praise to thy name, O thou most High.
Psalms 32:11
(11) Be glad in the LORD, and rejoice, ye righteous: and shout for joy, all ye that are upright in heart.
Psalms 40:16
(16) Let all those that seek thee rejoice and be glad in thee: let such as love thy salvation say continually, The LORD be magnified.
Psalms 64:10
(10) The righteous shall be glad in the LORD, and shall trust in him; and all the upright in heart shall glory.
Psalms 70:4
(4) Let all those that seek thee rejoice and be glad in thee: and let such as love thy salvation say continually, Let God be magnified.
Psalms 104:31
(31) The glory of the LORD shall endure for ever: the LORD shall rejoice in his works.
Psalms 118:24
(24) This is the day which the LORD hath made; we will rejoice and be glad in it.
Psalms 122:1
(1) A Song of degrees of David. I was glad when they said unto me, Let us go into the house of the LORD.