Your job is to never deviate from the system’s rules.

This is very important consistency when trading based on probabilistic thinking, which allows you to collect samples of trades under the same conditions and make probabilities work for you. If you followed the rules, the loss in front of you is part of the system and forms the edge you are trying to extract, so there is no need to lament any result. The wins, losses, and even no trades that come from following the rules all form an important part of the edge you extract from the system.