Nothing really "pushes" us through it, that metaphor doesn't really work. More like it "happens" in the universe around us.

One answer is entropy. This might help:

https://en.m.wikipedia.org/wiki/Entropy_as_an_arrow_of_time#:~:text=Entropy%20is%20one%20of%20the,can%20increase%2C%20but%20not%20decrease.