How can I learn to focus at one thing at the time???

I think I´m one of the most unstable persons I know. I get distracted in 2 seconds and can very rarely finish one project before I start a new one…. and what happens then….. OHH YEAH….I can´t finish any of them. Bad bad habit.

Any one out there who have any good recipe on how to be less restless not so easy distracted???????