You say you aren’t as grateful as you should be for the blessings in your life, and you would like to take steps to acquire this virtue.
Gratitude is at least partly a function of need: The greater our felt need for X the greater our gratitude—or the greater in any case is the opportunity or occasion for gratitude—when we finally receive X. Hence the importance of fasting from food and thus also the importance of times of chastity and abstinence within a healthy marriage. The “insensate brute” you’ve detected in yourself must first be curbed and then transformed; self-mastery precedes self-transcendence. One thinks of C. S. Lewis’s Great Divorce and the lizard that was changed into a horse. But this can happen only if we make a regular practice of not giving in to the desires of the moment.
The Fathers all say that the belly is where the problems tend to start. It’s a good practice, if this seems to be the root of one’s own brutishness, to make a habit of not eating to satiation. Leave the table a little hungry—not so hungry you’re physically uncomfortable or distracted by growling until the next meal, but just enough so that you’re reminded of the fact of your dependency on the gift of food. Knowing as you sit down to a meal that you’re not going to eat “all you want” will also make the food you do eat taste better—this of course is a common experience—and it’s much easier to be thankful for things that are tasty!
It should go without saying, but it’s also important not to “multi-task”: When you’re eating, pay attention to each and every morsel—don’t just shovel food in. I think of the Zen disciple who, when he asked about the true meaning of Zen, was told by his master, “When you are hungry, eat; when you are tired, sleep.” “But doesn’t everybody do this?” he objected. “No,” the master responded. “When they eat, they think of ten thousand things, and when they sleep, they dream innumerable dreams.”
A final word: You said you want to acquire the virtue of gratitude, but be careful here. No virtue is ever ours, never something we can appropriate and claim as our own. On the contrary we should enter into gratitude and the other virtues, endeavoring to participate in them as fully as possible, but with the knowledge that they belong to God. Rather than wanting to be perfect we’re better advised to want not to be imperfect.