It's amazing, actually.
With every action we make, there is a reaction on the world's future in some way or form. Almost like skipping stones over the surface of a pond, the ripples causing a disturbance in the water as the expand outwards.
With each decision we make, we alter the course of our world, leaving behind ripples on it's surface. But, they're not just your decisions that decide fate, but also the decisions of both humans and nature alike.
The choices made in the past are what curved the present as well. Just a slight difference such as one less butterfly could lead to a whole new outcome and all new scenarios we must face, the same goes for our future.
Although, not all ripples have good outcomes. Some of the choices we make can be good or bad, maybe even neutral, and impact the future with different magnitudes- even if it was not the direct cause, but maybe a small factor that played a part.
Yes, we can't exactly change the past, but we have the power to change the future. Although, it's up to you whether the choices you make today and from now one is a good one, even if it only led to a minor outcome.