Feeling good (ie. happy, loving, thankful, passionate, joyful, excited, hopeful, satisfied, or any other positive emotion) attracts more positive things, just as feeling bad (ie. unhappy, hateful, resentful, bored, depressed, fearful, worried, angry, critical, or any other negative emotion) attracts more negative things.
So if you want more of the good things in life, start to make feeling good a priority.
How, you may be asking yourself, do I do that when everything sucks? Start by acknowledging whether you really want to start feeling good again. If you don't want to feel good, you won't, but if you tell yourself "I want to feel good!", then you will start to attract that.
You may find your mind wandering back to negative thoughts. If you feel you can't switch back to thinking of something positive, find something that "makes" you feel good, and do that! Some tricks, which you have probably used many times already, are to listen to music that feels good, watch a funny movie, pet your dog or cat, take a walk in nature, or call a friend that cheers you up. Of course, you could also watch "The Secret"!
I've attached some uplifting videos that make me feel awesome. I hope they help you feel good too!