Learning any new skill takes practice and exercise, mindfulness included. I recently learned a simple exercise from the very clever Ruby Wax. It's called CUES.
Focus your attention on your breathing whenever a specific environmental cue occurs. Here's how I've been using it: whenever I get an unexpected text notification, I use that cue as a reminder to bring my attention into the present moment for a few breaths.
Choose any cue that works for you. "Perhaps you will choose to become mindful every time you look in the mirror. Perhaps it will be every time your hands touch each other, or every time you hear a bird chirp." I've played around with using the hourly NPR news recap as a reminder. The options are endless and individual.
If you're already focused on the present when a mindfulness cue hits, that's great and carry on. It isn't to distract you from the present, it's to snap you back to the present when your mind might otherwise be spinning in every other direction but now.