What you focus on you feel. If the same thing is repeated it can become who you think you are. We can become who we fear we might be or become who we hope we will be.
If we think the worst will likely happen then our brains will look for evidence of this being true. If we think the best will happen then our brains will do the same. Thinking positive is clearly the better option.
There are a lot of positive things we can be grateful for. The Sun came up today, as it has every day of your life so far and for many many years before you arrived here in your life. If the Sun disappeared I have heard it said that in 18 hours all life on Earth would be gone.
The Sun is essential for life to exist on this planet, yet we rarely spare a thought for how fortunate we are that all life on Earth gets another day, and another day, and so on.
If you begin the day just being grateful for the Sun rising, you might find other things to be grateful for and you will likely have a good day, because your mind will look for evidence for it.
The Fullfilment Project 