I've noticed in the past that when I move to a new city and new home, I tend to feel uncomfortable and even a bit scared for the first three days. For the first three weeks, I'm just somewhat uncomfortable, still adjusting to my new surroundings. After that, I'm generally OK.

I was interested to learn recently that that three-week period came up in a similar context: building a new habit. Some experts believe that it often takes about 21 days for people to adjust to big changes.

Now before you wonder what this has to do with investing, keep it mind that for most of us, there are some critical changes we can make in our lives that will make us more successful with our money.

Here are some new habits that can serve you well:

  • Reading annual reports regularly. This is how big investing names such as Warren Buffett and Jim Rogers have gleaned many insights. It's how you can get and stay on top of many industries. If you're interested in profiting from the growth in medical devices and robotics, for instance, the reports from Medtronic (NYSE:MDT), Stryker (NYSE:SYK), and Intuitive Surgical (NASDAQ:ISRG) will give you lots of insight. Similarly, if the oil industry interests you, look at what ExxonMobil (NYSE:XOM), ConocoPhillips (NYSE:COP), and Chevron (NYSE:CVX) have to say about their experiences.
  • Saving and investing more. You might, for example, put $10 in an investing jar every day, taking it to the bank every now and then, and investing in stock whenever it totals several hundred dollars. That daily $10 will come to $3,650 in a year -- and if it grows at 10% per year for 25 years, it will become almost $40,000. If you save and invest that much each and every year, you'll top $385,000 by 2034! You might end up with more, if you choose some stocks well. Over the past 20 years, for example, the not-that-exciting company PepsiCo (NYSE:PEP) has averaged nearly 12% annually, turning a one-time $3,650 investment into more than $33,000.
  • Spending less. There are lots of ways to get that $10 each day. Two to four of the dollars might come from your coffee habit, if you get into the practice of making your own brew at home each morning instead of buying it on the road.
  • Investing smarter. You might also develop new investing habits -- perhaps not letting yourself buy a stock until you write down why you're investing in it, and after you've studied it from many angles. Cutting out impulse buys can improve your performance considerably.

How to develop those habits
So now that you have a few habits you want to develop (including, perhaps, going to bed earlier, playing tennis, and eating more vegetables), how long will it take you to really make them stick? Three weeks? Well, maybe not. A study in the European Journal of Social Psychology offers a new look at that question. It found that:

  • The time it takes varied in their sample from 18 to 254 days.
  • The time it takes depends on various factors, such as how hard the new habit is to do, and how good you are at developing new habits. (Some of us are more resistant than others.)
  • New habits become much more automatic in the first days and grow more automatic more slowly, eventually hitting a plateau, after which they just won't get much more ingrained. On average, this plateau is 66 days.
  • It's OK to miss a day here and there.

So there's good news for us here. It may not be easy to develop a new habit, but it can be done -- and it can be very worthwhile and profitable, too. Just stick with it for more than a few days, giving it a chance to take hold. You could see your investing results improve significantly.

Trying to time the market is a habit you should break. Listen as Tim Hanson talks about his experience with market timing.

Longtime Fool contributor Selena Maranjian owns shares of Intuitive Surgical and PepsiCo. Intuitive Surgical is a Motley Fool Rule Breakers pick. Stryker is a Motley Fool Inside Value recommendation. PepsiCo is a Motley Fool Income Investor pick. The Fool owns shares of Medtronic and Stryker. Try any of our investing newsletters free for 30 days. The Motley Fool is Fools writing for Fools.