It's what you choose to see and notice that dictates your mood, rules your world and gives you impressions of life. Being thankful is a choice, so choose to be thankful.
Need a picture example? Here it is:
You can look out of your hotel room window and choose to have an apartment building view. Or you can look better and notice your hotel's perfectly lovely inner yard. The choice is all yours.
You can look to the right and see not such a lovely roof of the building nearby... Or you can look to the left and notice a gorgeous sunset. The choice is all yours.
Photos by me: first two taken in Milan, last two taken in Moscow and are what you actually see looking out of my parents' bedroom window.