Left-handedness doing exerecises

Why won’t my left hand cooperate?
It can be frustrating that the left hand can’t seem to fall into the groove with the right. But there are a few reasons why left-hand cooperation isn’t second nature.
The non-dominate hand
If you’re left-hand dominant, your left hand is more awkward than your right. Try switching the pen to your left and print your name. Some fumbles are bound to happen.
And if you are left-hand dominant… well, you may have an advantage over the rest of us.
Not the melody line
Some pieces switch things up and give the left hand the melody. But, most often, the left hand is just playing back up. This means the left hand gets a lot of harmony notes and chords. Our ears can help us fill in gaps with the melody line and tell us if we are on the right track. In harmony, it’s not so cut and dried. Our eyes and ears have to work harder to find the right notes. This can make it harder for the left hand to keep up.
The bass clef
Your left hand mostly hangs out in the bass clef. This means you have to think backward as you find the notes going down from middle C. Going up with Every Good Boy Does Fine is one thing. But, bringing the notes down from Good Boys Do Fine Always is another entirely. Not only do your fingers get a workout, but so does your brain!
More stretches and more notes
You often have more notes and bigger reaches in the left hand to top it off. It might have four notes to play simultaneously, then hop down to C2 and back up for another chord.
This means your weaker hand is doing more work in unfamiliar bass clef territory. That’s a lot for your left hand to tackle! But, with a few tips and the right exercises, you can strengthen the left hand to play its part.
Must-Try Left Hand Piano Exercises For Beginners
For the best coordination in your left hand, try out these tips:

Squeeze a stress ball.
Strengthening the muscles in your weaker hand can help it perform better on the piano. A stress ball is a great way to improve your left hand (while you release stress). This exercise can help your piano playing even when you’re away from the piano. 
Before you touch the piano keys, use a stress ball or other finger exercises to warm up the muscles in your left hand.

Play block chords as broken chords.
Three-note block chords, called triads, are very common in the left-hand music line. To ensure your fingers find the right notes easily, you can expand these chords by playing them as individual notes.
A good exercise is first to play the block chord as it’s written. Then play each note individually up and down and end on the block chord. Go through the bass clef in the sheet music with this practice. When you are done, play the music exactly as written. After that workout, your fingers will be ready to attack the keys!