The mind is basically a pattern recognition machine.
Here is a firsthand demonstration. Close your eyes after reading the next sentence and try to answer the question. How many things in the room or space you’re in are the color red? Open your eyes and look for red…
Did you see more red? How much green did you see?
The brain’s primary mode is scanning for patterns. In fact, cognitive science shows — we don’t interact with reality but a useful construction of patterns representing reality. If we don’t intentionally give it a task or pattern to scan for usually it will look for threats or problems — this is known as “scanning and landing” of the default mode network (DMN). (See The mind’s default mode (DMN) operates by “scanning and landing”.)
This is a tool to improve happiness too. Change the way you look at things what you look at will change. Change what you look for what you find will change. Look for achievements, opportunities, blessings, beauty, etc.