Rejoice in the Lord always. Again I will say, rejoice! Let your gentleness be known to all men. The Lord is at hand. Be anxious for nothing, but in everything by prayer and supplication, with thanksgiving, let your requests be made known to God; and the peace of God, which surpasses all understanding, will guard your hearts and minds through Christ Jesus.
In my years of teaching first grade Sunday school, I've seen joy on children's faces many times. Their joy is never predictable, never forced, but always immediate and genuine, for their minds are uncluttered by the perspective of adulthood.
Frequently their joy is expressed when they walk in the room smiling, knowing they are in a place of acceptance and love. Sometimes it's pride in a drawing they've completed, and given their best effort. Sometimes it's the hugs they give each other (and me). And sometimes this joy is expressed in prayer, which usually goes something like this:
Thank you for my family. Thank you for my dog. Thank you for letting me have a sleepover tonight. I hope I get a (insert popular toy here) for Christmas. Please help my grandmother feel better soon.
These prayers, so honest and pure, demonstrate the complete trust in God that comes easily for children but is sometimes difficult for adults. And yet trust is essential for us to experience joy.
God wants us all to trust in Him, and to know that He will take care of us no matter what happens. He wants us to come to Him with our worries and concerns. He is our refuge in all things, and the source of true joy in our lives.