I spent almost 2 years on learning how to trade and from my experience there are two aspects as well internal and external.
External:
One of the fundamentals of day trading is to keep emotions always out of the equation. The market moves by fear and greed, hence only those can win in the market in long run who come with a strategy and commitment, not with emotions. You too recognize this when you say "Anger, fear, greed, vanity all play major rolls in the downfall of a trader".
There are fundamentals of day trading to not let price fluctuations overwhelm you. If you follow them, you'll have less anxiety.
Internal:
Trading is all about mental discipline. A trader should be working like a very advanced robot. And to be able to follow all the rules of trading laid by your trading plan and your trading strategy you need to have good control over your thoughts and emotions. Meditation does help with that. Detachment from your work and practice of meditation in conjunction should be able to help. With growing mindfulness, you'll be able to realize at work that you cannot control prices even if you want to. So, you'll have no choice but to stick to the plan and strategy.
Mindfulness has definitely helped me stay calm and not be swayed by whatever is happening in my surroundings easily.
To detach yourself from work you need to realize that you are not a day trader at least not when you are away from your trading setup.
Also, understanding that you cannot influence price if you keep staring on the screen and if you eventually want to and have to stick to your plan and strategy then why not set limit orders and enjoy something else during robots do their work.
It is a process and it grows gradually. You also need consistency for it to work. Because initially the state of calm doesn't last very long. Only after you practice for few months you'll be able to see how not doing it anymore is far worse than when you had your practice up.
