That is an excellent question! I LOVE it when people ask good questions here! Thank you for that.
Everyone has a bad day sometime. Mine have gotten fewer and farther between. For me, one thing is that I look at what is causing it. If I woke up up with depression, I know it is the enemy and I open my front door and kick him out of my house.
More often it is because people are not doing what I want them to do when I want them to do it! I have to give those situations back to God.
My nature is to be depressed, but I have found something lately that is really helping me. I receive a devotional every morning from http://www.joelosteen.com
. He is the most positive person I have ever known. He has found all the positive scriptures in the Bible and brings them alive! I also watch him on TV on the weekends. I have read one of his books, "It's Your Time", and can't wait to either read it again or get others. I really suggest you get tuned into Him.
In the meantime, think about all you have and how good God is. I am praying He will change you today and bless you bunches.