Things we want to do - easy or hard?
What makes us think that anything we want to do is going to be easy to achieve, or hard for that matter, or anywhere in-between? I reckon the chances are that it will be harder than we think, not easier. And I reckon you can probably multiply the degree of difficulty by at least 5, maybe more, because once you get started on a project, any number of things will happen. Maybe the computer will break down, someone will get sick, you won't quite have the skills you need, or you