Take up drums at age 56?

@n80, the way to strengthen your left hand is to lead with it. If you are practicing rudiments (do it on a practice pad, rather than sitting at your set), play the "R" parts with your left hand, the "L" with your right. Set your kit up backwards, forcing yourself to play left handed and footed. It will feel very awkward and you'll suck at it, but it will bring your left hand and foot closer to your right. Did you know that although Ringo set-up and played right handed, on his fills he led with his left hand? Weird!

Leading with the left hand is a great way to practice.

You can strengthen your left wrist by starting slowly on the practice pad using only your left. Do single strokes, doubles, triplets and keep proper form. 

@n80, I just recalled a piece of advice from an old master I read years ago: when going about your everyday life activities, use your weak hand instead of your strong one. Brushing your teeth, opening doors, cooking, even try writing with your lesser hand. Using it more will develop it's abilities, the same way your better hand developed.

@bdp24 , @lowrider57 , good advice guys. Will start working on those things because this is never going to work well until I improve the dexterity of my left hand.

I am also learning drum notation. Not sure how useful it will be but it is not hard to learn.

I found George Stone Killer exercises with accents worked best for me. It forced my left to be the equal of the right. Accents helped me keep the hands relaxed and use the weight of the stick and rebound. Repetition creates muscle memory. Use a soft or gel practice pad - less rebound forces you to use better technique.

I use Sound Brenner metronome app and play 100 bars at half a bar R handed and half a bar left handed, then repeat 100 with a full bar each hand, then 100 again one bar and a half each, and final two bars of 1/8 th notes for 100 bars. This is at a low metronome setting which is then increased by 5 bpm and the whole thing repeated again and so on and so forth - gradually increasing speed by 5 bpm until I feel tension or start mucking up. I alternate between playing evenly at various volume levels and between accent both the first and last notes played with each hand.

STAY RELAXED

Of course everyone is different.

Also don’t underestimate how long it will take to get strength and strong nerve feeling in the left hand. We are talking years of work with several hours a day.

I would say that starting with proper technique is essential - bad habits take time to correct and have a way of returning as soon as you are pushing hard.

Hold the sticks like a bird in your hand - gentle pressure from index and thumb with the other fingers cradling your bird  - barely touching and providing a spring-like counter balance to the rebound. Control is a combination of wrist and those other fingers. Snapping the wrist down and squeezing the other fingers can create powerful accents and a great rebound if you train to accept the stick rebound (relax hand as the tip hits the skin)