Another teacher gave me slightly different advice which complements it very well, I think. It was basically like this hierarchy of needs, although he called it "a Jesuit's advice".
Basically, before worrying about work you need to make sure your body and mind are healthy. You are fed, have no injuries, your emotional and social life is in order and then you can work and be productive.
You could take this as an excuse to be lazy, but I take it as making sure your foundation is solid so your house doesn't crumble.