I think it depends on the person. It's going to affect everyone differently. There are also different types of weed - some types make you more energized and some types make you more chill.

If I'm feeling depressed and I smoke, I feel the need to clean up and more inspired to create something. Which is a good thing.

Also anything in excess amounts isn't good. You don't want to depend on something to be motivated or to get a good amount of sleep.