You’ll see many books with “21 days” somewhere in their titles. In many of these titles, it has to do with good habits that the author is going to try to help you accomplish. The reason for the 21 days is that is the number of days you need to perform tasks for them to become ingrained in your brain.
Most of these authors will tell you this number is based on scientific studies. Whether this is true or not is irrelevant. When you perform the same tasks for 21 days, they will start to become a routine. The problem with setting a hard number to this is people may abandon it after they reach the threshold. In other words, if you do something every day for 21 days, after the 21st day, you may feel as though you accomplished the task and move on.
A better approach for adopting new habits is to set up a plan that is longer term. Have milestones for the short term but project out for a much longer period. This way when 21 days passes, you still have a game plan to reference. This gives you something to shoot for after that time.
Another tip is to find people who are trying to form the same habits as you. Create times when you can all talk together, either in person or via some conferencing solution. It’s easier than ever to do this with the Internet. The members of this group can discuss what has worked for them and what has not been successful. Avoid the unsuccessful tasks. Try to keep the groups small. Large groups will force many members to become complacent and defer to the stronger personalities.
Whether you are working with a group of people or by yourself, maintain a journal to record your progress. This is for your purposes only so you can structure it however it works best for you.
If all else fails, you can seek professional help. There are plenty of coaches and mentors available to give you some guidance. Make sure you are critical when choosing a coach and hold them accountable. Set up milestones and as long as you are following their guidance, question any milestones that you don’t meet. Make sure your coach and you both know what is expected of each other and have any provisions in place before you get started in case it doesn’t work out.