We are grateful when we initially receive things and we know that it makes us feel good, yet we lose it over time. What gives?
Unfortunately for us modern humans, emotions are an evolutionary system that tells the body and mind how to react to given stimuli. So, if there is a threat, your fear drive kicks in and you act accordingly. If you eat food, you experience pleasure that tells you to keep eating it. This system is both a signal and reward system for your body. As such, it would not work if it were always in the positive direction—hugging a crocodile that might bite your arm off because you feel affection for it is not a good life decision. As such, your emotional state has to reset—to a point that psychologists call the Hedonic Treadmill—so that your body can be ready for the next need to act (remember, your body has to rest for about 8 hours per day).
Gratitude is a “social emotion” along with shame, embarrassment, guilt, etc. in that it evolved as part of humans’ relationships with each other—pro-social emotions incentivize you to act in ways that keep you in good standing with the group. If you are doing something that others disapprove of, it is to your genetic advantage to stop doing it to maintain your relationships. Similarly, if someone does something for you that you like, it is important to convey your appreciation or approval so that you can continue to see that behavior.
But, unfortunately, those social emotions are still subject to the hedonic treadmill—i.e., you can “get used to” anything. People acclimate to their environment, from adjusting to a new climate to dealing with a difficult relationship. This applies to good things as well, making you assume what you have to be a given—i.e., taking it for granted—and, therefore, no longer expressing appreciation for it. This can make long-term beneficial people and things to be difficult to maintain enthusiasm for because it can seem to become old and stale. This effect is usually positive—once you reach a goal or attain a thing, your feeling of accomplishment has to subside enough for you to set the next goal. However, when something requires maintenance to keep in good condition, this can be disastrous if you fail to take those necessary steps. In the worst-case scenario, you might lose the person or thing you took for granted, and the all-too-real pain of him, her, or it being gone will now surface to the point that you remember that you did appreciate it at one point.
So, what can you do about this to get the benefit while avoiding the drawbacks of this evolutionary system? Well, you can look at appreciation as a habit, not (just) a response to stimuli. The fun thing about advanced cognition is that you can choose where to focus your attention and what you think about. As such, you can choose to look at things you like and think about how much you like them. This will bring back feelings of appreciation. While not necessary, you can also imagine life without them long enough for the negative feelings to kick in where the feeling of appreciation comes back when you have it again. By remembering why you like things and focusing on the positive aspects of what you have in your life, you foster a feeling of appreciation and will, therefore, act better as a result. You will also be happier with your life overall since you will remember everything that you have to be thankful for instead of thinking about what you don’t have that you think you should (which is the source of negative emotions if strong desire is combined with negative beliefs).
I have a saying, “Always be content; never be satisfied.” It is my reminder that you always want to be striving for more, but you don’t want to take what you have for granted. You can do both—that is what continuous growth is all about. You are glad you can walk and that you learned to walk but now you want to run a marathon. Those can both be true. If you focus too much on not being fast enough yet, you will feel bad. If you focus too little on how much you enjoy the freedom of movement, you will take it for granted. You can see here how much of a delicate balance it is, and you have to find what works best for you.
There is an episode of FRIENDS that points this out: a character played by Alec Baldwin appreciates everything to a socially inappropriate extent. Everything is amazing! The others get annoyed by his awe at otherwise common things. You can look and say that Alec Baldwin’s character is being ridiculous or that the main characters are being unreasonable for reacting in such an annoyed way at his positive attitude.
While I can’t tell you who is right there or what the optimal balance will be for you, all I can say is that practicing appreciation (maybe to the show’s point, practicing it silently) is a good habit to ensure that you both are happier overall with your life and you treat the things you care about with more care than you otherwise would if you began to take it for granted. While you might not be able to focus on how wonderful it is to breathe air every second of your existence (or you couldn’t get anything done), it might make sense for you to take time every day to practice appreciating everything that you have in life and have an emotional regulation mechanism where you begin to “count your blessings” whenever you feel down. These habits will reduce the degree to which you take things for granted and help you with your overall sense of well-being in life.