When a circumstance or situation comes your way that seems to deflate your joy - do what David did: Strengthen yourself in the Lord.
How do you do this? Following David's example, begin with praise.
Praising God even (or especially) when you don't feel like it is SO important. It's a true sacrifice - a sacrifice of praise! We should not be led by our feelings (our soul), we are led by the spirit. Our soul - our mind, will and emotions - should not rule us. Let your spirit rule and praise God inspite of the yucky thoughts and feelings going on in your soul.
Open to the book of Psalms and find a God glorifying Psalm of praise to God and begin reading it, or singing it aloud. Keep praising Him with His Word.
Put on some hymns or praise songs that usually ignite your soul - even if they don't today - sing them as if you were in the mood to sing them. Set your mind on God as you praise Him. Don't dwell on the things of this world, focus on God - the truth of His Word and His love for you, His desire to deliver you and help you and bless you.
God ordained praise as a blessing for us. The army of the Lord defeated the enemy with praise (2 Chron 20:22). Through praise, God also defeats the enemy. Remember, our battle is not against flesh and blood - and the enemy cannot stand against us as our voices are raised in praise to our Lord - declaring how great and mighty is our God.
When situations or circumstances try to defeat you, strengthen yourself in the Lord with praise.