Here's my take on habits, merging everything I've read with lots of personal experience and self-analysis of my habits.
Some habits are easy to create, but that's not just bad habits. It's a real joy to kinda fall into a habit that provides something positive in life, that wasn't that hard to do. Like my career in Technical Writing. Not that there wasn't a lot of work. There was. But not the soul-wrenching struggle that I've had with other habits that I've tried to make or break.
Taking smoking for instance. Started when I was about 13. Quit dozens of times - for a while. Once for about two years, and then started back again. But when I finally really quit - at the age of 58 - it was pretty darn easy.
What I've notice about habits, good and bad, is that they start with just choosing to do or not do something. And then choosing it again. And again. Usually not every time at first, but when I've just kept choosing a particular action/behavior, one that has a desired result, it becomes reinforced over time. Not always as quickly as I'd like, or as painlessly as I'd like, but eventually it sticks. And it may not look like what you thought it would. Sometimes life without the "bad" habit seems weird and uncomfortable for quite some time. Or a "good " habit might seem awkward and unfamiliar as it develops.
But we are, as humans, creatures of habit. We might as well learn what habits are and how to make and break them.