Like meditation, gratitude has the ability to change your life. I started practicing gratitude daily about 5 years ago and it completely changed my life. I wasn't a miserable person by any stretch but since incorporating gratitude into my life I have been able to appreciate my life rather than worrying about my life.
There are two components to gratitude.
The first is the affirmation of something good in our lives and the second is that gratitude forces us to look outside ourselves (outside of the ego) for the good.
Gratitude can have transformative effects because it allows us to be present in the moment. It encourages us to appreciate the value of what we have. The more we can appreciate that value, the less likely we are to take it for granted. Gratitude also has the tendency to block negative emotions like jealousy, resentment or regret because you cannot feel grateful and resentful at the same time.