Gratitude or appreciation is often used as a law of attraction technique in order to manifest more of what we desire in life. But I believe there is a catch to this.
When expressing appreciation in order to manifest something, the appreciation should not be expressed with anxious excitement. Instead, appreciation should be accompanied with feelings of calm, peace, joy and fulfillment. Do not confuse excitement with desire by the way. A strong desire is, well, desirable when focusing on manifesting more things into your life.
However, being too “excited” implies that it is not normal to have the thing you desire, especially if eager anticipation is causing that excitement. And sometimes being too grateful (or thankful) about something implies feeling that you aren’t worthy of it. So stay away from feeling that what you are receiving is too good for you.
Basically what it comes down to is this — The universe does not respond well to neediness.
So think of the thing you want in your life as a normal occurrence, something that is naturally evolving into your life, as if the universe had intended to provide it for you all along. 
