Thoughts are habits, and these habits need to be interrupted so they can change. I will suggest two activities; refocusing and thought stopping.
to refocus, I am going to suggest sitting down with a notebook and a pen to write down ten things about your life that you are grateful for. Once you start to pay attention to the things in your life that are working well, your energy will shift and you will start to attract and create more things that are working well. This may be hard to do at first, but everyone can find at least ten things. It may be that you are thankful for this website that offers free advice. Perhaps you are thankful to have access to the internet and all of the resources it gives you. You can be thankful for your health (your eyesight, your healthy kidneys, the ability to hear, the ability to walk), you could be thankful for possessions (the clothes you wear, your vehicle, your home), it could be qualities you possess (your great sense of humor, or insightfulness, your caring nature, your confidence). Brainstorm at least ten things. Do this every night before you go to bed.
The next activity is thought stopping.
This practice takes some time to cultivate. As soon as you notice yourself thinking about how bad your life is, say “STOP!” “This does not serve me”. Then replace those thoughts with positive thoughts that contradict the negative thoughts. These thoughts will include things from your “thankful list” or you can check out the following website to create some of your own positive affirmations http://www.vitalaffirmations.com/affirmations.htm#example%20affirmations
Once you have a few positive thoughts to replace the negative thoughts, you may want to write this practice out so you have it handy when the negative thoughts show up.
It will probably take a few weeks before you will start seeing results, but once you start taking active control over your thinking, you will notice change.