Developing an Attitude of Gratitude should be a "Piece of Cake" for an Observant Jew. After all, we wake up declaring: "Modeh ani l'fanecha!"
Thanksgiving is central to our prayers and our holidays. Our life-cycle events recycle this theme again and again. Saying "modim anachnu lach" at a minyan is up there with answering Bar'chu and "Y'ehei shmeih rabba"
But even a very good Jew can often use a "booster shot" in raising one's awareness, in raising one's consciousness.
The regular daily dose does meet the "minimum Daily Requirement", but sometimes we want to achieve "spiritual excellence" [kudos to R Yaakov Feldman] and minimums leave us in stagnant mediocrity unless we grow past it.
Nu - so how do we administer such a booster shot?
I'm glad you asked!
Some Tehillim have Gratitude\Thanksgiving as a theme
Hallel - 113-118 [esp. 118]
Hallel haGadol -136
To name a few
One may bookmark these and recite them as constant reminders.
How about some Brachot in Davening?
Besides the Modeh Ani - which was adapted from EloKai! N'shamah
There are other classics -
Elokay! N'shamah itself
Gomeil Hassadim Tovim
Nodeh L'cha in Bentsching
Nishmat kol Chay [an expanded intro to Yishtabach]
Y'hall'lucha [end of Hallel]
When you are obligated to say them, say them with extra kavvanah
When you are not obligated, one may merely contemplate upon one or more as a spiritual exercise.
EG take Elokay! N'shamah and read it later in the day w/o using the Sheim and Contemplate its theme.