Halt the mental spiral immediately. Resist the urge to forecast failure or project the problem into the future (e.g., assuming a DNF is inevitable). Recognise the reality of the moment neutrally, keeping your mind firmly in the present.
Pinpoint the precise nature of the issue. Is it a mechanical injury (e.g., sprained ankle), a navigational error, or physiological distress (nausea)? Strip away the emotional panic to identify the specific root cause.
Gauge the severity of the problem against your available assets.
Formulate an immediate fix. If you are facing a 'triad of troubles', prioritise the issue most likely to end your race (such as hyperthermia) first.
Implement the solution instantly. Action paralyses fear and prevents freezing. Put rubber to the trail and keep moving forward, however slowly.