This is actually an EASY one. There have been several studies about practicing gratitude and how it benefits people. There are TWO major benefits of practicing gratitude--contentment and joy.
But here's the deal, it has to be a PRACTICE. So, it's not an "attitude of gratitude," but actual behaviors. Here are some suggestions:
1. Start a gratitude journal that you write in everyday.
2. Set a timer on your phone/watch and at a certain time each day, take a moment to think of all that you are grateful for.
3. If you already have a well-established scripture/prayer time, incorporate gratitude into that time. So, before or after you read the bible, list all that you're grateful for, OR before/after you pray consider all that you are grateful for.
4. Make a gratitude bulletin board (or you can use your fridge). On little slips of paper, write down what you are grateful for and put it on the board. Add to it each day.
5. Same as above, but put it in a jar. Add to it each day, and take time to read through them once a week, once a month, etc.
6. Do a "gratitude challenge" with a friend. Each day email or text each other a list of what you are grateful for.
etc.
etc.
Ultimately, you have to work it for it to work. Take on a regular practice and you'll begin to notice that your envy diminishes and your joy increases.