You always want to be able to trade another day.
If you really want to trade then you should never put yourself in the position where you have lost your trading capital. One of the most frustrating feelings is when you want to trade and you can’t because you lost most of your trading account.
One idea would be to set daily trade limits. If you lose $400 (or a set % of your account) you close all trades and turn off your computer and stop trading for the day. You need to reflect on what has happened to you and get yourself back into trading shape emotionally and physically.