korien_apr12“I enjoyed the first half of the book but then I just lost my momentum, so I haven’t finished it yet.”
“He tried to stop but his momentum carried him into the intersection, and he almost caused an accident.”

When an object is moving, it keeps going at the same speed unless something stops it. We say the object has momentum. You can use it as a metaphor, too. “We didn’t really love each other anymore, but we just kept on as we had been going because of momentum.”