Left-handedness. Doing exercises

Lift weights with your left hand. One of the best ways to strengthen your left arm and hand, and correct any strength imbalances between your dominant and non-dominant sides, is to lift weights.

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  Hold a dumbbell in your left hand and do exercises such as bicep curls, kickbacks, hammer curls and dumbbell presses.
  
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  Start with a low weight, then move up to heavier weights as your strength improves.
  

Learn how to juggle. Learning how to juggle using three and then four balls is a great way to strengthen your left hand and arm, while also providing you with an impressive party trick!
Practice bouncing balls. One great exercise for improving ambidexterity and strengthening your non-dominant hand is to take two table tennis rackets and two balls and to bounce them simultaneously with both hands.

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  Once you master this, you can progress to using smaller rackets, or even wide-ended hammers.
  
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  In addition to improving your left-hand usage, this is a fantastic whole brain exercise![7]
  

Pick up a musical instrument. Many people who play musical instruments (which require the use of both hands) are already somewhat ambidextrous.

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  As a result, picking up a musical instrument -- such as the piano or flute -- and practicing everyday will help you to strengthen your left hand.[8]
  

Go swimming. Swimming is another ambidextrous activity which has been proven to help with balancing the brain hemispheres, allowing you to use you non-dominant hand more fluidly.

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  Hit the swimming pool and do a few lengths to strengthen the left side of your body and get a great cardio workout at the same time![9]
  

Wash dishes with your left hand. Washing Dishes regularly with your left hand is a safe and simple method to improve on the dexterity of your non-dominant hand. This can be both fun and useful in the long run, apart from cleaning the dishes.
Start doing finer motor tasks such as mirror writing, playing pool, cutting cords out of shrimp, and throwing darts with your non-dominant hand now that you practiced it up with simple tasks. Doing that will also practice up the general skill of automatically transferring skill from an action to its mirror image so that the next task you start doing with your left hand that you used to do with your right hand, you will be a tiny bit more skilled at doing it with your left hand when you first start than you would have been if you had never done it with either hand before. It may take many years for your left hand to catch up to the skill of your right hand but probably less than 2 months for your left hand to become very nearly as skilled as the right hand. Once your left hand becomes skilled enough to do the job easily, there's no need to be impatient about your left hand becoming more skilled just because your right hand is even more skilled. You can skip the steps 2-7 if you want to hurry up and become ambidextrous and can handle the boredom of doing them slowly at first. Remember to use your left hand at all times. Using your dominant right hand has become so ingrained in your brain that you will use it automatically, without thinking. This can be a problem when you are attempting to become left-handed. To overcome this problem, try to come up with a system to remind yourself to use your left hand whenever you do something.

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  For example, write the word "left" on the back of your left hand and the word "right" on the back of your right hand. This will act as a visual reminder every time you go to pick up a pen or complete some other activity.
  
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  You could also try wearing your watch on the right wrist instead of the left. This will really help your subconscious to register that you are trying to change sides.
  
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  Another thing you can do is place sticky notes on things like the phone, the refrigerator, and the door handles. These will remind you to use your left hand whenever you reach out to touch them.