"JOY means Jesus first, Others second, Yourself last."
Even if you aren't a Christian, put your religion first, whatever that may be. A great way to do this is spend the first few minutes of the day in prayer or meditation. Start the day off in calm, peaceful manner that will hopefully continue on throughout the day.
Next, focus on others. Direct your time and attention to your family, friends and others in your life. Spend time building others up, motivating and encouraging them. Volunteer your time to help others.
Put yourself last. Now I'm not talking about all the time. I understand and fully believe you need to take care of yourself in order to take care of others, however, don't have YOU on your mind every minute of every day. Stop thinking "What about me?" or "What's in it for me?" all the time.
By getting your mind off yourself and onto others and Jesus (or your religion) you will start to see a bit more joy in your life. Enjoy it!