When you're a writer you need to write. You need to write to get your emotions out. It helps you make sense of strong emotions from anger to depression to elation.
When you're a writer you need to write to put characters on paper. What non-writers don't know is that writers have characters that are born in their heads and live in their heads and fight to get out when they're grown. If the writer doesn't get those characters out to live on the paper, the character will nag them like a little child crying, "Mom! Mom! Mom!"
If a writer doesn't write, they get antsy. It's akin to an addiction. You may get the itch to write. Your fingers may crave the feel of a pencil or the feel of computer keys beneath them.
Writing is a way of life. It's something a writer needs to do.