If you are thinking thoughts of shame, guilt, apathy, grief, fear, desire, or anger, your thoughts could lead to physical symptoms which only makes matters worse.
There is a self-debilitating concept I've heard promoted where there is a limited amount of joy, achievement, goodness, whatever, fill in the blank, and if you've gotten any of these you've somehow taken it from them.
For example, you see your neighbor pull up in their new car, what do you say to yourself? Assume you like your neighbor (which you should).
How do you react?
Wow, cool car! He totally deserves something nice, can't wait to go for a ride = I'm so happy for him!
Or
Whoa, what's he doing with that car, who does he think he is, how can he afford it? What a poser, must be mid-life crisis = I'm so jealous!
Yes, it's a simple example, but do you see the difference in the mental process there?
Life is simply too short to live one minute of it in the lower vibe emotions. How does your neighbor getting a car even affect you? It doesn't, you can be jealous or you can think, one day, I'll have something like that too. . . .or not, does it even really matter? When you get right down to it, it's just stuff and you can't take it with you when you go! I think I'd rather be enlightened, joyful, full of love and peace! And, that you can take with!!!
Full disclosure: This information is my opinion based on years of living life, having a strong curiousity level and my own experimentation. I am not a psycologist or psychic, just found happiness to be preferable to misery. Please consult with a professional if you have any questions.