A Zen monk doesn't lead lazy life : he wakes early and has day filled with work.
However, he doesn't have an unending task list either - there are certain things he's going to do today, and no more. If you do less, you can do those things more slowly, more completely and with more concentration. If you fill your day with tasks, you will be rushing from one thing to the next without stopping to think about what you do.
Keep yourself make busy is kind of mental laziness. It makes you to stop thinking and running on the hamster wheel which doesn't take you anywhere. Thinking where is your intention.