Negative thoughts, just like the Dalai Lama said are because of an I, I, I, self centered perspective, and also because of taking reality as it appears. Reality is not what it appears to be.
Reality is made up of our mind with perception, thoughts, and feelings.
Taking reality as it appears as negative is just believing the illusion of your perception.
You create your own reality. We have the power to instantly change anything from good to bad, black to white, just by changing our thoughts about something; by seeing it differently than you did before.
Heaven and hell are on earth, it is just based on how you perceive and view the world around you.
You can make any experience hell by focusing on the negative, and you can make it heaven by focusing on the positive.
Changing your perception of things can come by deciding on a bad day that it is actually a good day. If you truly believe that, the day will change.
You can also change your perception by acquiring new knowledge. Your perception and interpretation of that new knowledge is how it affects your reality. All knowledge is neutral, everything is neutral, we decide to put a label of bad or good.
There is no bad or good. To a “bad” person, they are doing what they believe and see is right for them. Same for a “good”person.
Everything in the universe is a beautiful blank canvas for us to create our reality on.
In conclusion, if you are having negative thoughts, change your mindset to having a positive and great experience and truly believe it. Your reality will change because we are the creators. We have the power, not anything external.