Right Arm is Stronger Than My Left Arm, Most people can lift more with their right arm than their left, simply because most of us are naturally right-handed. Similarly, left-handed people would usually be able to lift more with their left arm. So, most people have a slight imbalance to begin with when they first start bodybuilding.
You shouldn’t let this be a stumbling block for you – but rather, use it to tell yourself that you are GOING to do better!
To overcome this, you need to treat your weaker arm like a lagging body part, which means that you should focus on your weaker arm FIRST in your routine. Hit it ‘harder’ than your right arm. For example, perform all the dumbbell curls for your left arm before switching over to the right. At the end of your workout, you could also perform 1 or 2 additional sets of curls with your left weaker arm.
So, no matter which part of the body is weaker / lagging, in summary, the trick is to:
Work the weaker body part first
Perform extra reps / sets for the weaker body part
Eat well (Sufficient protein, carbs, healthy fats)
Get sufficient rest
My advice to you is not to focus and distract yourself too much on your weaker arm, but think of it as the opportunity for your weaker arm to catch up and be stronger, if not as strong as the other arm. Also, at the same time, don’t neglect other exercises (even if they are not related), such as Squats, Deadlifts, Chin Ups, Pushups, etc – they are the basics and play a crucial role in determining your physique!