Through the unfailing love of the Most High he will not be shaken.

Psalm 21:1-13
The king rejoices in your strength, Lord. How great is his joy in the victories you give!
He asked you for life, and you gave it to him—  length of days, for ever and ever.
Surely you have granted him unending blessings and made him glad with the joy of your presence. For the king trusts in the Lord; through the unfailing love of the Most High he will not be shaken.
Your hand will lay hold on all your enemies; your right hand will seize your foes. Though they plot evil against you and devise wicked schemes, they cannot succeed.
Be exalted in your strength, Lord; we will sing and praise your might.
The occasion may be a victory or an anniversary. The king counts his blessing, rejoicing in God's goodness. His confidence for the future rests in God's constant love. With God's help, all his enemies will be put down. The last verse is the counterpart to 2-"9. This time the people cheer God to the echo.
Why?
Rejoice in God's strength, for the victory is given by the Lord!
God listened to our prayer and give us much more than we expected.
Through God's unfailing love I will no be shaken.
God's mighty hands lead us to victory and against enemies, though they plot evil against the Lord, they cannot succeed.
Le sing and praise God, our might!

How?
Trust in the Lord and pray to my God for his mighty hands overcome all in the world.