Focus on the good in your life. I know it's hard, but it's worth counting your blessings and realizing how many people would be grateful to be in your position. The very fact that you can read this on a computer means that you have access to resources that the majority of the world's population can only dream about.
Reach out to friends and family. Often sharing your troubles with a sympathetic audience can help lessen the burden.
Empathize with others who have troubles in their own lives and try to help them. This includes not just your immediate circle, but others that you can help by joining or supporting public service organizations. Your own troubles will give you a good perspective on what others are going through, and you will feel better if you try to help others with their troubles rather than just focusing on your own.
When worries bog you down, remind yourself that "worries are tomorrow's troubles borrowed for today's consumption". Nothing is gained by worrying. If anything, worrying paralyzes you and prevents you from doing what you need to do to tackle your problems. It's not easy to stop worrying, but constantly reminding yourself of this fact really does help put things in perspective.Sometimes, life can really get you down. Whether it is because you're out of a job, or suffering some other personal misfortune, or just feeling bummed for no good reason, sometimes it's just hard to feel upbeat. However, this just compounds the issue. The sooner you can get out of this state, the more you can do something about your negative circumstances.