Full of Joy?

I was in English class a couple days ago and was given a printed blog post by another lady, Kathy Howard on God's Anti-Anxiety Prescription where she proceeds to give us some verses from Philippians 4:4-9.
"4Always be full of joy in the Lord. I say it again -rejoice! 5Let everyone see that you are considerate in all you do. Remember, the Lord is coming soon.6 Don't worry about anything; instead, pray about everything. Tell God what you need and thank Him for all He has done. 7Then you will experience God's peace, which exceeds anything we can understand. His peace will guard your hearts and minds as you live in Christ Jesus."
       I feel this is sometimes hard to do, to have joy all the time, especially when our circumstances seem to warrant a little worry or we're left feeling sad... Something I'm learning now; I think having Joy in the Lord is not always reflected on how we feel. We can feel terrible and still rejoice in the Lord (though happiness can still work in tandem with joy for the Lord), but it is that gratitude in rejoicing; to recognize all of the undeserved blessings and still be able to come to God as His child, servant and friend.
I was in a significantly down mood going to church the other day; I just wanted to be invisible. Though throughout the service, I feel God spoke through the sermon and the worship music to help me see things from a different perspective. I went from being cranky, to feeling grateful and humble for what I've been given. Also, there are a few people there who always manage to bring a smile out of me regardless of what I'm feeling. I'm grateful for that too.. ;)

When Paul says in verse 6, to pray instead of worrying, can also feel pretty difficult. When I care a lot about something or someone and what their going through, I know God listens when I talk to him, But I also know that He doesn't always have to answer my prayers in the way I hope... "Yet God has made everything beautiful [or amazing, joyful, lovely...] for its own time. He has planted eternity in the human heart, but even so, people cannot see the whole scope of God's work from beginning to end." Ecclesiastes 3:9. We will experience God's peace for trusting in him; again, not to say we necessarily feel calm, but that we know our Father in Heaven already has a plan for what's going on... that following Him will leave our hearts and minds full of the truth and His reassurance.