I am but one of seven billion people on Earth.
There are over one hundred billion galaxies in this universe.
Why does any of my actions have an impact?
Why is any of what I do significant?

If I helped one person out, it would not affect the universe.
Andromeda would not care if I helped one person out on Earth.
The universe does not care what one person does.

Helping a person out though, may affect them.
That one person's smile or show of gratitude may not change the universe at all but it would impact me.
It would help me see the result of my actions and remind me of the complexity of human emotion.
It would make me realize that even if the universe does not care about my actions,
Another person might;
This is what makes my actions significant.