The chunky monkey
You'll remember the first time you tried to change gears while driving: how co-coordinating all those movements felt as natural as patting your head while rubbing your stomach.
But now you can change gears so readily that you don't even notice that you are doing it. What happened? It turns out that repeating complicated manoeuvres changes both how and where they are stored in the brain. At first each element is stored separately. With enough repetition they are stored, as one movement, deeper in the brainbox.
Which makes sense because 'one movement', like changing gear, is itself made up of its own components; each of which would originally have been discreet muscle units. It only became 'one movement' through all that practice in using your arm.
The process by which your brain does this connecting is referred to as (stand by; technical term coming up) 'chunking'.
And Homo sapiens, the 'wise man', is very much the 'chunky monkey'. Chunking is by no means unique to us, but without it we would never have had the brainspace to text while driving, make cocktails while supervising small children or paint the Sistine Chapel. The good news, and the bad news, is that once the pattern is chunked, it is a habit and relatively unresponsive to change. In that way, practice does not make perfect. More accurately: practice makes permanent (of course we can still change it, but we all have experience of how much easier it is to form a habit than to later alter it). Recent research at MIT has shown that there are particular neurons in the brain that are responsible for marking the beginning and the end of 'chunked' units of behaviour. This 'task-bracketing' seems to be important both for initiating a learned sequence and for telling your brain that it is complete.
This underlines how difficult it is to break a particular habit. Neurologically it seems that "once you've popped, you just can't stop".
But there are three, sometimes linked, things that you can do much more readily.
Firstly, you know the kind of things that make you more 'jumpy'; things like stress, fatigue, hunger, caffeine and sugar. The more you can avoid them, the less reactive you are going to be.
Secondly, breaking any habit makes it easier to break others. So mess with your own head a little. Get out of the other side of the bed. Try brushing your teeth with the 'other' hand. Take a different route to work. In other words, play a little more. Play a little more through how you live. Lastly, all these things are easier if you take guidance from someone else (as long as their habits are not the same as yours). That might be an Alexander Technique teacher who can help you learn how to do everyday things with more ease.
Admittedly, patting your head while rubbing your stomach will probably still feel as difficult as... patting your head while rubbing your stomach.