Over the Next Month You Have to Work on an Intensive

Over the next month you have to work on an intensive project which will require focused mental work. Which will most likely help you to increase your well-being and productivity?

A) Put in maximum overtime at the beginning so you are not interrupting the flow of your focus.
B) Stop working at a reasonable hour and make sure you are getting adequate sleep.
C) Take frequent breaks, getting together with friends at least once a day.
D) Focus mainly on your project, but take Saturdays off and spend the whole day in physical activity.