A few years ago I decided to try to hack my perception, the same way Tim Ferriss hacks his whole life. I tried a bunch of different things, from cold showers (ouch, those were painful!), to fasting, from nootropics (LEGAL nootropics!).
What was the best one? Well, this page already says "Gratitude Journal", so you already know the answer.
But, truly, it was one of those things that improved my perception to much, so easily, and requiring no cold showers!
It makes sense though, stick with writing things you are grateful for every single day for a few days and, quickly, you'll find yourself having to think for a moment once you've covered the basics: friends & family, job, and perhaps my interests and hobbies.
What happens next? You need to think, and that's where your perception starts to be altered. Within a week, you'll notice your taking mental notes of small daily things you can be thankful of.
Now you're noticing beautiful things and focusing on every smalll little thing that happens in your life instead of noticing a fly that keeps poking at your nose or a the neighbor's barking dog who's waking you up at 5am.