Ah, Yes — the Hurdles
Individually, the difficulty is that even those with the best intentions occasionally become embroiled in their mental and emotional perspectives, some of which are distorted and reactionary. In this sense, no one is perfect; now and then we take a brief detour and create a mini version of hell on earth. We must also consider that some people have little interest in making others happy. That is why evolution, both personal and collective, is a step-by-step process. It takes time and practice.

Collectively, our problem is that when we elevate people to positions of power, they tend to grow greedy; they treat others as less than human. Historically, the devastation these seemingly soulless creatures have created through warfare — military, economic, and psychological — far exceeds the suffering even the most psychopathic but unempowered individual can inflict.

In any case, to make our legacy a "heavenly" one requires, at the minimum, a commitment to be kind to one another. We can take this a step further and say that as we train ourselves to transcend our egocentric habits and see beyond ourselves, we raise our consciousness. From a metaphysical perspective, when a person develops his or her consciousness, it energetically raises the collective unconscious — the overall state of humankind's psyche. This in itself is a noble and worthwhile pursuit. However, being kind to one another is not a community system that will help usher in Heaven on Earth. Rather, it represents the underlying attitude needed to make these visions a reality and to operate effectively, like moving from an industrial-growth society to a life-supporting society.

Conclusion
Thinking about what one will leave to the world is something older people do. That's partly because young people seldom seriously consider their own mortality. However, ignoring one's effect on others can lead to regret later in life: we are never too young or too old to consider our impact on the world. To complicate matters, it's hard to recognize the influence that we are having on others. Confucius, for example, died thinking that his teachings amounted to nothing. Conversely, we have leaders who believe history will remember their murderous exploits as those of heroes who "spread democracy."

On a grander scale, we can consider the spiritual evolution of the human race. This is not a one-person job — it's a collective legacy. Each of us is involved: we either inch the collective unconsciousness towards that goal or away from it. If we succeed in this project, we may even produce something more amazing than, say, the refrigerator.

Everyone can help create a joyous reality for others; and it helps to do this not for one's own benefit but for the cause, because that helps remove the ego from the equation. When we become self-less, something wonderful fills the void, and we become even more effective as the universe unfolds effortlessly through us.