Whenever we are upset, we think about something negative. The more we think about something negative, the more negative our thoughts become and the more upset we are. But we never tire of thinking. We think one thought after another and still create more thoughts. We never stop thinking. Our minds are never at rest.
This also means if we choose to think of happy things, we can think positive. The more we think about something positive, the more positive our thoughts will become and the more happy we will be. We will never run out of happy thoughts, some of which will change the way we look at things and give us ideas to overcome the negativity that hits us every day.