I happen to be taking a Team Lead course, and forming habits came up yesterday. 21 days weren't mentioned explicitly, the time frame was "a few weeks". We were given 6 criteria when forming a habit:
1. Tangible - you need to pick a tangible action that is observable. If you're trying to fix a part of your behavior you can't pick "I'll pay more attention" as a habit to correct yourself, instead you should write a note or say some phrase.
2. Up to me - don't form a habit that requires outside factors. If you want to start jogging, don't ask your neighbor to jog with you. Each time he's not available, you'll have an excuse not to jog.
3. Swallow the frog - don't push it off. This isn't a well defined criteria, the idea is to minimize excuses (like #2).
4. Daily - a habit needs to be formed by taking action every day.
5. Trigger - your action needs a trigger. This can be an internal (feeling hungry), external (a timer on your phone), or contextual (every morning, every time you walk into a conference room).
6. New - it's very hard to form a habit if you've already tried and failed. Pick an action that you haven't already tried.
There was also an important note that changing behavior often requires multiple steps. The instructor gave the example of using dental floss. It's hard to go from nothing to flossing every day, so break it into:
1. Every time you go into the bath room in the evening, pick up the dental floss, and put it down.
2. After picking up the floss becomes a habit, cut a piece of floss, and throw it out.
3. After cutting the floss becomes a habit, floss a few teeth.
1. Tangible - you need to pick a tangible action that is observable. If you're trying to fix a part of your behavior you can't pick "I'll pay more attention" as a habit to correct yourself, instead you should write a note or say some phrase.
2. Up to me - don't form a habit that requires outside factors. If you want to start jogging, don't ask your neighbor to jog with you. Each time he's not available, you'll have an excuse not to jog.
3. Swallow the frog - don't push it off. This isn't a well defined criteria, the idea is to minimize excuses (like #2).
4. Daily - a habit needs to be formed by taking action every day.
5. Trigger - your action needs a trigger. This can be an internal (feeling hungry), external (a timer on your phone), or contextual (every morning, every time you walk into a conference room).
6. New - it's very hard to form a habit if you've already tried and failed. Pick an action that you haven't already tried.
There was also an important note that changing behavior often requires multiple steps. The instructor gave the example of using dental floss. It's hard to go from nothing to flossing every day, so break it into:
1. Every time you go into the bath room in the evening, pick up the dental floss, and put it down.
2. After picking up the floss becomes a habit, cut a piece of floss, and throw it out.
3. After cutting the floss becomes a habit, floss a few teeth.
And so on.