Any action requires two kinds of effort in order to get done :

• An intrinsic effort that depends on the action.
• An effort to decide whether or not to execute the action.

Habits can modify the first, but the main reason they work is that they eliminate the second type of effort.

Every time you read a book, you’re investing these two kinds of effort. First there’s the effort of reading. Depending on the difficulty of the book, this might require a lot of effort or zero effort. Imagine the difference between a quantum physics textbook and a Harry Potter book and you’ll see why.

Any action requires two kinds of effort in order to get done:

• An intrinsic effort that depends on the action
• An effort to decide whether or not to execute the action.

Habits can modify the first, but the main reason they work is that they eliminate the second type of effort.

Every time you read the book, you’re investing these two kinds of effort. First there’s the effort of reading. Depending on the difficulty of the book, this might require a lot of effort or zero effort. Imagine the difference between a quantum physics textbook and a Harry Potter book and you’ll see why.

Habits appear to reduce these two costs in different ways:

1. Habits can reduce the intrinsic cost by making you better at the task. As you read more difficult books, you get better at reading, so it doesn’t require as much energy.
2. Habits reduce the decision cost by eliminating the ambiguity of when and how to perform the behavior. If you read your fifty pages at lunch, every day, for three months, the next lunch break you’ll automatically start reading without having to decide whether to do it.

For a lot of tasks, the second cost reduction is far greater than the first.

Habits, appear to reduce these two costs in different ways:

1. Habits can reduce the intrinsic cost by making you better at the task. As you read more difficult books, you get better at reading, so it doesn’t require as much energy.
2. Habits reduce the decision cost by eliminating the ambiguity of when and how to perform the behavior. If you read your fifty pages at lunch, every day, for three months, the next lunch break you’ll automatically start reading without having to decide whether to do it.

For a lot of tasks, the second cost reduction is far greater than the first.

• Not all habits are equally easy to build . This makes sense because some have higher intrinsic effort required, which results in not only higher intrinsic cost but also higher decision costs.
• You can’t establish an unlimited number of habits . This makes sense because even if you eliminate the decision effort, you still have to pay the intrinsic effort.
• Most habits are only metastable . Metastability is a concept in physics where a certain state of affairs is stable, but small perturbations can break that stability.

• Not all habits are equally easy to build . This makes sense because some have higher intrinsic effort required, which results in not only higher intrinsic cost but also higher decision costs.
• You can’t establish an unlimited number of habits . This makes sense because even if you eliminate the decision effort, you still have to pay the intrinsic effort.
• Most habits are only metastable . Metastability is a concept in physics where a certain state of affairs is stable, but small perturbations can break that stability.

This idea of metastability conforms to my experience as the reason why I’ve found few habits have had permanent lifespans.

• Inevitably, the habit breaks down because of a temporary lifestyle change: a vacation, an illness, needing to move or work overtime.
• These create shocks which are often enough to break the behavior, increase the decision cost, making it no longer automatic when you return to the habit.

• This metastability suggests that the most important positions to look at when setting a habit are during possible disruptions. If you temporarily have to break a habit, then re-establishing it as soon as the interruption is gone should be your top priority.

Even better if you can avoid breaking the habit at all, creating a placeholder habit in its absence. That might mean reading five pages instead of fifty when you’re busy, or doing a home workout when you’re traveling instead of going to the gym.