My method of dividing the tasks into two buckets is very simple. Is it fun? If it takes me more than 5 seconds to answer that question, it's not fun. Fun is easy to categorize. So the complement of fun is thus easy to categorize too.

The reason I break it down into two is because of how I look at tasks with respect to stress. Nearly every task either adds (even if slightly) to my stress or relieves it. Very few are on the border and if they are on the border, I'd say they add to my stress just because they're not actually relieving it. My goal is to mix it all up in a healthy balance that best suits my personality.