I know its a cliche to say you can choose your own happiness but its soo very true. In every situation its not what is happening its what we perceive is happening so for certain people they see the positives in all situations and others have it ingrained in them that “these things always happen to me” “ thats just my luck” but if you were to say those sentences with a positive frame when something good happens then you can continue to see the world in that way.
Start off small, notice when you get that gem of a parking space, or you go to get your favourite make up and its the last one in your shade. Take those wins and run with them.
If something you perceive is a negative thing see what you can learn from that situation and squeeze a positive out of it.
You know that friend you have that seems to have it all and jammy things happen to them. Its not luck its just that they choose to keep building on their positives and they deal with the negative stuff in quiet with reflection and inquisition to the lesson.