All of the habits that you have right now - good or bad - are in your life for a reason. In some way, these behaviors provide a benefit to you, even if they are bad for you in other ways.

Sometimes the benefit is biological like it is with smoking or drugs. Sometimes it's emotional like it is when you stay in a relationship that is bad for you. And in many cases, your bad habit is a simple way to cope with stress. For example, biting your nails, pulling your hair, tapping your foot, or clenching your jaw.

These "benefits" or reasons extend to smaller bad habits as well.

For example, opening your email inbox as soon as you turn on your computer might make you feel connected. At the same time looking at all of those emails destroys your productivity, divides your attention, and overwhelms you with stress. But, it prevents you from feeling like you're "missing out" ... and so you do it again.

Because bad habits provide some type of benefit in your life, it's very difficult to simply eliminate them. (This is why simplistic advice like "just stop doing it" rarely works.) Instead, you need to replace a bad habit with a new habit that provides a similar benefit.

For example, if you smoke when you get stressed, then it's a bad plan to "just stop smoking" when that happens. Instead, you should come up with a different way to deal with stress and insert that new behavior instead of having a cigarette.

In other words, bad habits address certain needs in your life. And for that reason, it's better to replace your bad habits with a healthier behavior that addresses that same need. If you expect yourself to simply cut out bad habits without replacing them, then you'll have certain needs that will be unmet and it's going to be hard to stick to a routine of "just don't do it" for very long.