You've been using your right hand all your life. Well, with the exception of the ten percent this whole article is backward for. Next time you do something you've grown to consider a single-command operation, try using the hand that isn't the one that wants to do it. Open doors, tie your shoes, write, all with one hand and not the expected one. Let's get into why.
For the bulk of us, basic tasks become as difficult as they were when we were kids. All your signals are backward and trying to go to the wrong hand. The brain is so used to saying "brush the teeth" that it has no idea what the actual steps are. You’re accustomed to clicking "back" in the web browser—but that doesn't mean you could define it easily.
In order to get past this stage, which essentially takes an attempt for a day and then some weird dreams, you need only try. It's fine to suck at it. What you're trying to accomplish is forcing the brain to keep the new connections that got used repeatedly (either successful or bad habits), and "delete" the useless ones. You'll suck a lot less when you wake up. I promise.
It isn't easy! You'll be forced into mindful actions, concentration, humility and a loss of the illusion of competence. By slowing down, you'll end up progressing in skills you work at this way. There are definite, demonstrable changes in the brain and body by building and using all of these new "functions." As you use and reinforce using your wrong hand, the other side of your brain gets used a lot more. The practical upshot here is increased "openness," creative thinking and problem solving, and the basic ability to feel the feels.
Change your whole life (no hyperbole!)
If this isn't your first time reading through something by me, you expect this sort of article to answer the ever-present "but, why?" Up until around the mid nineties, lefties in German schools were forced to write with the right hand anyway. There was a study following a group of adult left-to-right converts and a second group of right-handers who always were. After everyone had spent a good couple of decades, a PET scan was done and uncovered a difference between the groups. Fitting the reasonable hypothesis, the converts had a stronger activation in the other side of the brain. Really, this could be a lot of things. It could even just be a method of suppressing the instinct to use the hand you were born into using. That said, there are practical uses to re-learning the basics. Whatever you pair with the practice will itself be relearned. Go have some fun!