My practice began with a journal, writing a few things I was grateful for each day. That evolved into being an active part of a small community of women who practice together, via daily emails. And from there I began encouraging everyone that eats meals in my home (even the most reluctant of teenagers) to practice gratitude before dinner.
It's a beautiful practice. Formalize it for better results.
Here's how it works: No matter how shitty your day, you make a list of at least ten things you're grateful for. Every single day. No matter what crappy time you are having. If your fridge is full of food and your body is healthy enough to type your list, that is two things you can include in your list. Every day.
Sometimes it might seem contrived and forced. Sometimes you won't want to write the list and do your best to avoid it. If you're able to stick to it for just a few weeks, though, something magical happens with your perspective. Your mind changes. And you begin to sub-consciously look, every day, for things to add to your list.
You'll know you've got the hang of it when you get a flat tire and even though you're pissed you'll write on your list that night "Im grateful it was not raining as I waited for triple A to come."
The bottom line... you are the architect of your experience. The world is not coming at you, it's coming from you. Change your perspective, change your life. Be well.