When we were children we didn't always understand our parents' and teachers' rules. Children are naturally self-centered, and even the most obedient child doesn't always get the "why" of the rules, even if they do follow them. So we couldn't really be blamed for not always behaving and keeping in line.
As we grow up and mature, we usually start to appreciate why the adults in our lives did what they did, and why they chose to implement certain rules. We begin to recognize that what we didn't consider important as children was in fact serious; and the opposite is true too -- what seemed like a big deal to the child version of ourselves turns out to be really insignificant once we've matured and learned to appreciate the bigger picture.
We also learn that our actions have consequences, and that following the rules is for our own benefit. That's why what seemed to be an insignificant act could have serious ramifications, and a seemingly greater deed will not. It's because our immature minds were simply incapable of grasping the depth of certain matters, and as our minds develop, both biologically and due to lived experiences, we become capable of appreciating the less obvious benefits of following those rules.
Another thing we learn as adults is that being given something for free, without any effort on our part, is inevitably going to be less valued on the recipient's part. Children, on the other hand, expect everything to be done for them, and as parents we will usually give in fairly easily. But as we grow up, we learn to appreciate the value in earning our keep. Something you worked for and earned is going to be far more cherished than something you received without any effort.
In other words, what really happens to us as adults is that over time we start seeing things from the perspective of our parents and teachers. That realization allows us to bond with them differently than we did as children, as we are now capable of seeing things from their perspective.
As always, these lessons can be clearly found in the Torah. In his final weeks as leader of the Jewish people, Moses reminds them that the time has come for them to grow up. For forty years, the nascent Jewish nation was developing and maturing, not always appreciating the value of seemingly small mitzvahs, nor understanding why their actions elicited various reactions from G-d. They had also gotten used to their every need being filled without having to lift a finger.
But now, Moses tells them, you are big kids, on the cusp of becoming adults. It's time that you discovered the value of each mitzvah, how that seemingly small act can bring you tremendous blessings, and that in fact your actions can make the world a beautiful place.
And with time, the Jewish nation continued to mature. The Torah consistently describes blessings to be bestowed upon anyone committed to following G-d's commandments, as small and as insignificant as the individual deed may seem.
But our perception of the mitzvah's value isn't what matters; what really makes a difference is how G-d views it, and our willingness to do the right thing. We may not see the significance from the outset, but as we keep at it and we discover the direct results of our actions, we prove that we have matured beyond even our own expectations.
And the more we do and the greater our commitment, the more grown up will become. And the more grown up we become, the stronger our bond with G-d will be.
That unbreakable bond, which in truth was always there though perhaps concealed at times, will become most apparent with the coming of Moshiach, when we will witness the ultimate results of our mitzvah observance today. That's when we will become truly grown-up.