Record and learn from your mistakes and losses. If you are trading stocks, futures, options, forex or cryptocurrencies like bitcoin or ethereum, you certainly make losses and mistakes when trading.
Write them down and see how much each is costing you. Avoid them and you can update the record to see how much you saved.
Set a penalty (for example no trading for a day or a week) and a reward (fresh juice, spa treatment or nice day out) for committing or avoiding each mistake.
Practice avoiding all of your mistakes for a week and get good at protecting your capital. In trading more important is protecting your capital than making money.