While stuck in the horror of a Nazi death camp, Viktor Frankl discovered that the last human freedom was the ability to choose one's attitude. Just look around and find five things for which to be thankful. Don't go to sleep tonight without thanking these people. They will feel great, and so will you. I've never met the soul that didn't appreciate being appreciated.
Most folks can go a long way on a little appreciation.
If you have trouble finding something to be grateful for, consider the abundance of resources that are available to us, such as the public library. A library card gives you access to information on just about anything you would want to learn or know. I think being ungrateful, feeling sorry for yourself, whatever you want to call it, restricts our vision in life. An attitude of ingratitude teaches us to focus on lack. The more we focus on lack, the more lack we see, and the more our vision is restricted.