Wasted coffee

Why is it that I always forget to drink my coffee once it's down to about an inch or two left in the cup? It's like there's a bit in my brain that gets flipped when the coffee is getting low and it makes me stop realizing it's there even when there are a few good sips left. Then, thirty minutes later, I look at my cup, realize there's coffee left, take a sip, and it's cold and shitty.