Out of date

Apparently, I am behind the times. I was taught to, and have till this moment, always follow periods and colons with a double space. I was just researching this online, however, and have found that it is now proper and acceptable to have only one space after any kind of punctuation mark, that to do anything else is old fashioned. I'm going to have a hard time putting this into practice as I've spent years typing and have always pushed the space bar twice after a period!